Custom Metal Stamping Parts

1.1. Standard for die clearance of stamping parts

The clearance of stamping die is related to the material type and thickness of stamping parts, among which unreasonable clearance is likely to cause the following problems:

• The gap is too large. Stamping parts of the burr is relatively large, the overall quality is poor.
• The gap is small. Although the quality of punching is better, but the wear of the die is more serious. The service life of the die will be greatly reduced, and it is easy to break the punch in the stamping process.

Reasonable clearance can extend mold life, enhance discharge effect, reduce burr and flanging:

Material	Min.	Best	Max.
copper	8%	12%	16%
brass	6%	11%	16%
Low carbon steel	10%	15%	20%
Aluminum	5%	10%	15%
Stainless steel	15%	20%	25%

1.2 how to improve the service life of stamping die

1. Select a reasonable bottom die gap according to the type and thickness of the material;
2. Reasonable mold structure;
3. Lubrication should be done when stamping;
4. The mold is treated with special surface treatment, such as titanium plating, titanium carbide nitride;
5. Reasonable use of mold adjustment gasket;
6. Appropriate use of bevel edge mold;
7. Check the wear of die base before stamping;

We are here share you 16Analysis of common problems in “Metal stamping parts” dies:

2.1.   Scrap jumping for the metal stamping products

1) The length of the punch is not enough. Cut the punch into the die with a punch edge and add 1mm to replace the punch.

2) The die gap is too large, the cut-in reduces the gap or reduces the gap with the coating machine

3) The punch or template is not demagnetized, and the punch or template is demagnetized with a demagnetizer.

2.2. Metal stamping parts Waste material Jam caving

1) The punching and blanking hole is small or the blanking hole is biased to increase the blanking hole. Smooth metal stamping parts blanking tooling to solve the problem

2) The blanking hole has chamfering. Expanding the blanking hole and remove the chamfering

3) Without taper. Make the “metal stamping products” tooling taper or reduced the length of the straight wall.

4) The straight wall of the knife edge is too long. Drill the back side to short the length of straight wall.

5) The edge of the blade collapses, causing the burrs of the metal stamping parts too big. re-grinding the cutting edge

2.3. Poor appearance with metal stamping products

1) The edge of the blade collapses, causing burrs of metal stamping parts oversized. Re-grinding edge

2) The clearance between the punch and the die is too large. Adjust the clearance and make new

3) The metal stamping product die has a poor finish. Polishing the straight edge of the die

4) The clearance between the “metal stamping parts” punch and die is too small. Adjust the clearance again.

5) The top push material force is too large. Change the spring and reduce the top force.

2.4. The metal stamping parts trimming edges are not in order

1) The “metal stamping products” tooling Positioning offset. adjustment positioning

2) There is unilateral forming, pulling material to increase the pressing force. Adjust positioning

3) Feeding is not allowed. Adjusting the feeder.

4) The feed step is calculated incorrectly. Recalculate the step and re-set the position

5) Incorrect design, resulting in uneven knives. Re-cut the cut edge, the knife edge with insert.

2.5. The “metal stamping parts” tooling punch is fragile

1) Improper positioning of the material causes the punch to cut unilaterally, or the feeding device is broken due to uneven force. Adjusting the positioning.

2) Improper positioning of the material, causing the punching punch to cut unilaterally, adjusting the positioning or feeding device due to uneven force

3) The lower mold waste blocks the knife edge, causing the punch to break. Re-drilling the large drop hole to make the blanking smooth

4) (playing board) offset. The fixed part (plywood) of the punch is trimmed with the guide part or re-cut block to make the punch smooth up and down.

5) The plate is poorly oriented, causing the punch to be unilaterally stressed.

6) The punch edge is too short to interfere with the plate. Re-change the punch to increase the length of the blade.

7) The punch is not fixed properly, and it is tilted up and down. Re-fix the punch so that it cannot move up and down..

8) The punch edge is not sharp. Re-grinding the edge

9) The surface of the punch is strained, and the force is uneven when the material is removed.

10) The punch is too thin, too long, and the strength is not enough to change the punch type.

11) The punch hardness is too high, the punch material is wrong. Replace the punch material and adjust the heat treatment hardness.

2.6. Iron filings with the metal stamping parts

1) The rib is misaligned. Recalculate the rib position or bend position

2) The bending gap is too small to extrude iron filings. Re-adjust the gap, or grind the forming block, or grind the forming punch

3) The bending punch is too sharp. Repair the metal stamping products tooling R angle

4) There is too little material for the connection of the knife. Reconnect the knife

5) The rib is too narrow. Re-grinding the rib

2.7. Metal stamping parts forming bad

1) The forming die is too sharp, causing the material to crack. The forming punch is repaired by the R angle, and the R angle is properly corrected at the edge.

2) The length of the forming punch is not enough, resulting in failure to form the metal stamping products. Calculate the correct length of the punch to adjust the actual length of the punch to achieve the type requirement

3) The forming punch is too long, and the material at the forming part is deformed. Determine the correct length of the punch and adjust the actual length of the punch to meet the requirements.

4) Insufficient material in the forming section of the metal stamping parts, causing cracking. Calculate the unfolded material length of the metal stamping products, or repair the R angle, or reduce the forming height of the stamped part.

5) Poor positioning, resulting in poor molding. Adjust positioning or feeding device.

6) The forming gap is too small, causing cracking or deformation.

2.8. Bending size of the metal stamping part

1) The mold is not in place, causing angular errors or dimensional deviations. Adjust the closed height or angle

2) Insufficient elasticity, resulting in poor angle, dimensional deviation. Change spring

3) The material does not meet the requirements, resulting in poor angle. Change material or re-adjust gap deviation

4) Material thickness deviation, causing poor angle, size deviation. Determine material thickness, change material or re-adjust gap

5) Improper positioning, resulting in dimensional deviation. Adjusting the positioning to make the size OK

6) Design or processing error, resulting in a gap between the bending blocks. Repair welding grinding, eliminating the gap between the blocks, resulting in small bending size

7) Forming the male R angle, the bending height is smaller under the angle and other normal conditions.

8) Two-sided bending size of metal stamping parts is too large

9) Unilateral bending and pulling material cause metal stamping products dimensional instability. Increase spring force and adjust positioning

10) The gap is unreasonable, causing stamped part poor angle and dimensional deviation. Repair clearance

11) The height of the sheet metal stamping part folding knife is not enough. The folding punch is too short to cause the angle to be bad. Increase the height of the folding knife so that the bending punch can fit into the folding knife as much as possible.

12) The speed is too fast when bending, which causes the bending root to deform. Adjust the speed and choose a reasonable speed.

13) The structure is unreasonable. The folding knife is not set in the fixed template. When the folding knife is set into the template stamping, the gap becomes larger. Re-milling.

14) The hardness of the forming heat treatment is not enough, causing the pressure line to collapse.

2.9. No discharge material of the metal stamping parts tooling

1) Improper positioning or improper feeding. Adjust positioning or feeding device

2)Not enough space to avoid. Repair the metal stamping parts tooling to get enough space.

3) The inner guide column is strained, resulting in poor plate movement. Replace the inner guide column

4) The punch is pulled or the surface is not smooth. Replace the punch.

5) The top material pin arrangement is unreasonable. Re-set it again

6) The top ejection force is not enough, or the stripping force is not enough. Replace the top spring

7) The punch and the splint are not smooth of the metal stamping tooling. Repair plate and the splint to make the punch fit smoothly

8) The molding slider is not well matched. Repair The slider and the guide groove to make it fit smoothly.

9) The heat treatment of the plate is unreasonable. After the stamping for a period of time, the deformation is re-polished and correct the plate to correct the deformation

10) The punch is too long or the length of the ejector pin length is not enough. Increase the length of the pin or change the length of the punch.

11) The punch is broken. Replace the punch

12) The template is not demagnetized. Demagnetization.

2.10. Metal stamping parts Feeding is not run smooth

1) The mold is not in the right position, causing the strip is not on the same line with the feeder. Mold re-laying or adjusting the feeder

2) The belt is not flat. Adjust the leveling machine or replace the material.

3) If the material is not discharged, the feeding will not be smooth. Refer to the unloading solution.

4) Positioning is too tight. Adjust positioning

5) The pilot pin is too tight or the straight wall is too long. Adjust the pilot pin

6) The punch is not fixed or too long and interferes with the tape. Change the punch with the correct length and re-fix it.

7) The top pin is too short and the strip interferes with the formed block. Adjust the length of the top pin to avoid interference.

8) The position of the lifting block is improperly arranged. Adjust the position of the riser block

2.11. Poor mold riveting of the metal stamping parts

1) The mold closing height is improper and the riveting is not in place. Adjusting the closing height

2) The workpiece is not in place, positioning deviation. Adjust positioning

3) Confirmation of defective workpiece before riveting. Check the workpiece to ensure that the workpiece is ok.

4) The length of the riveting punch is not enough. Replace the punch with the appropriate length.

5) The riveting punch does not meet the requirements. Confirm and use the riveting punch that meets the requirements.

2.12. Missing assemble the punch header of the metal stamping products tooling

1) Install the wrong punch header of the metal stamped parts

2) The punch has no direction mark. Mark the direction of punch

2.13. Use Improper screw of the metal stamping products mold

1) Do not know the thickness of the template. Measure the length and thickenss of the template

2) Not careful enough, lack of experience. Use the appropriate screws

2.14. Disassembly and assembly the metal stamping parts mold

1) The pin holes are not wiped clean. Clean the pin and hole. When disassembling the mold, first remove the positioning pin. Using the screw to guide the pin, then disassemble the pin.

2) The order of loading and unloading the mold is incorrect. Do not hurt the pin hole when disassemble the pin.

2.15. Locating pin of metal stamping parts mold

1) The wall of the hole is galling during the metal stamping process. When assembling the mold, carefully check whether the hole is galling, otherwise it should be reamed to right size.

2) Pin hole offset or no escape hole for the location pin. Make the escape hole for the location pin

2.16. The spring of the metal stamping parts tooling is too long

1) Did not pay attention to the depth of the spring hole. Measure the depth of the spring hole and calculate the compression of the spring.

2) Not careful enough and lack of experience. Choose the right spring

3.1. Why do we need to maintain sheet metal stamping press?

The maintenance of sheet metal stamping equipment is just like the maintenance of your car every time, and it also requires daily maintenance.

In order to prolong the metal stamping service life of the press and ensure the accuracy of the press, the user must properly perform the daily maintenance work of the press. Maintaining and maintaining the press not only helps to ensure the quality of sheet metal stamping parts processing, but also reduces equipment failures; it also helps to protect the operator’s personal safety and reduce the occurrence of safety accidents.

The daily maintenance of the press is mainly infiltrated by the daily work of the metal stamping operator. Routine maintenance is mainly required for metal stamping equipment operators to do in every shift:

• Check carefully before and after the class.
• Wipe all parts of the equipment, and refuel on time and quality to keep the equipment clean and lubricated.
• The equipment is used strictly in accordance with the operating procedures, and the faults are eliminated in time, and the handover work need done well.

3.2. Specifically, there are mainly the following aspects of metal stamping maintainance.

3.2.1. Before starting work of metal stamping process

1. Clean up the workplace. On the press table and around the press, work-independent items must be cleaned and the workpiece and blank placed in position.
2. Check the friction parts of the press and the lubrication parts for wear. The oil cup should be filled with lubricating oil. 3 Check whether the metal stamping die installation is accurate and reliable, and whether the stamping tooling cutting edge has cracks, dents and notches.
3. The motor must be started after the clutch is disengaged.
4. Test whether the movements of the brakes, clutches and manipulators are flexible, accurate and reliable, and do several empty strokes. After confirming that it is correct, start normal work.

3.2.2. During work

1. When working, remove the stamping parts and scraps on the workbench at any time. When cleaning, use special tools such as hooks or brushes. It is strictly forbidden to remove directly by hand; during work, two sheets cannot be punched out at the same time.
2. Turn the oil cup of each part by hand and fill it with oil.
3. When drawing deep, care should be taken to add lubricant to deepen the drawing, and pay special attention to the cleaning of the material.
4. When the press is not working properly, if the slider is abnormally dropped, there is abnormal impact sound, continuous rush, and the finished metal stamping product has burrs, etc., stop working immediately, turn off the power supply, find the faulty part, and then work properly.

3.2.3. After the metal stamping work is completed

1. Separate the clutch.
2. Turn off the power.
3. Clear the debris on the workbench.
4. Wipe the oil on the press and the die, and apply anti-rust oil on the metal stamping die and press.

4.1 Metal Stamping parts machine maintenance project introduction

4.1.1 Air pressure of  “metal stamping  products” equipment

• Air piping: Check if there is any air leakage in each pipeline.
• Air valve and solenoid valve: Check whether the air valve and solenoid valve control are normal under proper operation.
• Balance cylinder: Check if the air leaks and check if there is proper lubrication.
• Die pad: Whether the air leaks, check if there is proper lubrication, and check whether the fixing screws of the die pad are loose.
• Pressure gauge: Whether the needle of the press is normal.

4.1.2 Electrical parts with sheet metal stamping parts machine

• Electrical control: check controller and operational response, problematic control. The condition of the device and operation, and the controller in question is replaced. Loose Partially tighten, check if the fuse is of proper size, check the insulation of the wire for damage, and replace the defective wire.
• Motor: Check if the fixing screws of the motor and bracket are tightened.
• Button and foot switch of stamping press: Check these switches carefully and replace them if they are bad.
• Relay: Check the wear of the contact, the loose disconnection of the knot, etc. Please take care of the maintenance carefully.

4.1.3 Lubrication system on stamping parts mold and punching

• Air lubrication component of the clutch for metal stamping mold: Eliminate all the accumulated water, check the condition of the single piece and add the lubricating oil to the correct position.
• Lubrication system for metal stamping process: Check whether the lubrication lines are broken and worn, check the fittings for loopholes, cracks and damages, and check each oil level meter to inspect the oil. Whether the height of the surface is up to standard. In normal operation, the oil-immersed gear is changed once every three months. Clean the oil tank once every six months (about 1500 hours).

4.1.4 All mechanical parts on metal stamping press

• Table: Confirm that no foreign objects are placed between the table and the bed. Make sure that the table lock screws are not loose, and confirm that the level of the table is within the tolerance.
• Clutch: Whether there is a leak, check the wear of the piece, etc.
• Drive gear: Check if the gear and key are tight, check if the gear has proper lubrication
• Adjust the slider of metal stamping press(electric type): Check if the slider motor is firmly fixed and confirm the automatic. Is there any problem with the brakes? Check if the worm and worm gear adjusted by the slider are accurate.
• Adjust the parts (manual): to check if the gears adjusted by the slider have normal lubrication. Check if the holder has a failure condition and check if the mold height indicator is accurate.
• Motor drive: check whether the motor shaft and the pulley are loose. Whether the belt and the pulley are crack wear and deformation.
• Clean the stamping press: Clean the inside and outside of the punch to remove any accumulated foreign matter.

4.2 Operation and maintenance precautions in maintenance the metal stamping parts equipment

4.2.1, Daily inspection metal stamped press essentials

It is mainly carried out before and after the daily operation, which is subject to 10 hours per day, and should be suspended for more than 10 hours.

4.2.1.1 Check item: Pre-work check

Before the main motor starts:

1. Is the oil supply sufficient for each part?
   Before the mechanical activities, the amount of oil in the lubricating system oil circuit must be filled. You can fill it with a handful of hand-operated buttons, and check whether the oil pipe is broken or cut. Please pay attention to the oiling parts.
2. Whether the air pressure meets the specified pressure?
   Whether the clutch air pressure (0.45-0.50Mpa) is sufficient, should pay attention to whether the air pressure changes or not.
3. Pressure adjustment valve is abnormal
   When the air pressure is introduced or the pressure is changed, it is necessary to confirm whether the secondary pressure meets the selected pressure. If the failure fails to control the selected pressure (it will rise once), the dust on the valve seat of the adjustment valve must be disassembled and washed.
4. Whether the operation of the solenoid valve for clutch or brake is abnormal
   The clutch is driven by the inching operation and the exhaust sound of the solenoid valve is used to verify whether the action is normal. Piping connection (joint, etc.) or clutch cylinder.
5. Air pressure leaks
   Check if there is any leaking air.
6. Pressure vessel (including balance cylinder) water discharge

4.2.1.2 After the main motor starts for stamped press

1. Check of flywheel rotation
   Pay special attention to the starting condition, acceleration condition, vibration and sound (slow for more than 5 seconds). When the rotation resistance increases, the V belt will vibrate.
2. Full operation check
   Before the operation, confirm the presence or absence of abnormality by inching, safety—stroke, continuous operation, emergency stop, and foot-operated operation.

4.2.2, weekly inspection pressed equipment essentials

The operation rotation time is once every 60 hours. In addition to the pre-recorded daily inspection preparation requirements, the following inspection and maintenance must be carried out for metal stamping parts machines.

Inspection item: equipment

1. Cleaning of the air filter
   Disassemble the metal mesh inside the filter (but the on-site piping system can be implemented once every two weeks without serious water accumulation). When the filter is plugged, the air pressure cannot rise.
2. Electrical equipment (PLC; contactor; relay, etc.) inspection
   Loose terminals, oil, dust, etc., contact conditions and other insulation are normal, check and maintain.
3. Check if there is any abnormality in the wiring
   Check and maintain whether it is damaged, broken, knotted, loose, etc.
4. Cleaning of various parts
   Oil spills, dust, debris, etc. are removed, and the inspection is checked for crack damage.

4.2.3 Monthly inspection metal stamped parts equipment essentials

The inspection and maintenance should be carried out every 260 hours of the monthly use time. In addition to the daily and weekly equipment requirements, the following inspection and maintenance must be carried out.

Check item: equipment

1. Clutch, brake stroke measurement
   Whether the stroke of the clutch or brake is within the range specified in the manual, please measure the adjustment.
2. V-belt tension check for main motor
   The V belt is checked by hand and the tension is about 12 mm deep.
3. Balance cylinder inspection
   Disassemble and inspect for damage and lubrication of metal stamping press parts.
4. Top dead center stop position confirmation
   The top dead center stop position is inaccurate for the following reasons. Adjust according to the following conditions.:
5. Although the stop position is certain, but the top dead center is not closed, the position of the micro switch should be adjusted.
6. The stop position is uncertain, but when the error range is not too much, please adjust the brake stroke.
7. The stop position is uncertain, but if the error range is too much, please adjust the cam fixing screw or related contact parts.

Inspection the equipments during metal stamping process

• Pay attention to the oil supply status of each part
• Pay attention to air pressure changes

Post-work check

• Cleaning, cleaning, and inspection of all parts
• During the metal stamping operation, please pay attention to the oil supply status at any time. The manual or automatic oil pump works normally, and the oil flow from the oil distributor is normal for each oil path. Do not cause heating damage to the guide rail of the crankshaft bearing sliders due to oil failure.(Except for motor heating, the temperature is limited to 60 ° C or less.)
• During the stamping operation, always pay attention to the pressure gauge to indicate that the pressure is within the normal range, to avoid the working pressure is too low, and the machine tool continues to be used, resulting in clutch damage.
• The locking bolts should be tightened to discharge the dirty water and release the air pressure of the air cylinder. At the same time, all parts should be cleaned and the inspection should be checked for cracks or damage.

3.2.4 Annual inspection of the whole Metal stamping machine essentials

Each year, the whole machine is inspected and maintained in 3000 hours. In addition to the various inspection items recorded before, the following inspection and maintenance must be carried out. Due to the different working conditions of each machine tool, the wear and damage of each part are different. Therefore, it is necessary to have skilled maintenance. Personnel or professional service personnel are required to assist in the implementation of thorough inspection and maintenance.

Check item:  sheet metal stamping equipment

1. Precision check
   The slider guide gap 0.03mm is added up to not more than 0.08mm.
   Verticality of the metal stamping tooling  (the verticality of the sliding stroke to the plane of the tabletop):
   0.03/100 (nominal force ≤ 630KN); 0.04/100 ((nominal force >630~2500).
   Parallelism of the stamping mould (parallelism of the smooth bottom surface to the plane of the table):
   0.02 0.06/1000×L2 (50 TONS or less); 0.03 0.08/1000×L2 (50-250 TONS).
   Comprehensive clearance of stamping parts tooling(0.7m/m) or less (50-250 TONS):
   L2: slider (front and rear, left and right) width (m / m); L3: stroke length (m/m)
2. Clutch, brake decomposition check
3. Solenoid valve inspection
4. Are the basic screws checked for looseness?
5. Inspection of electrical components

• The wear amount of the friction lining, the inspection and measurement of the wear condition, the degree of wear of the inner and outer flank surfaces, the inspection of the degree of friction of the spring and the inner surface of the cylinder, and the repair or replacement of defective or damaged parts.
• Whether the metal stamping operating condition is normal, whether the coil is burnt or not, the spring must be checked for abnormality, and it must be repaired or replaced when the problem is detected.
• Please lock the foundation screws.
• Check the PLC and relay contacts, loosen the wires, disconnect the wires, etc., and carefully carry out maintenance.

4.3 Electrical part maintenance checking for metal stamping press

4.3.1, Daily maintenance matters with custom metal stamping

• Is the punching operation stop position normal?
• In the cam sending box, the proximity switch and the cam are fixed and the gap is normal.
• Rotating cam switch, whether the transmission mechanism of each part is worn or loose.
• Emergency stop button, whether the action is normal.

4.3.2, Monthly maintenance matters for custom metal stamping process

Cam mailing box inspection

• Is the fixing screw loose?
• Is the distance between the cam and the proximity switch detection surface appropriate?
• cam and proximity switch, whether there is water, oil or dust and other debris attached.

Operation button switch check

• Whether the joint has oil and dust attached.
• Is there any oily dirt and dust on the sliding part, and the movement is smooth?

The electromagnetic valve check

• Whether there is foreign matter in the coil and exhaust part.
• Is there any discoloration in the coil part?
• Check if the O-ring is damaged and the movement is smooth.

4.3.3, Metal stamping parts presses Every half years of maintenance matters

• Check all kinds of safety devices and check whether the action is true.
• Is the solenoid valve switch normal?
• Inspection of important relays.
• In the wire connection socket, whether the wire welding part is working normally.
• Does the pressure switch part operate normally with machine?
• Inspection of each terminal.

4.3.4, Annual maintenance matters of custom metal stamping manufacturer

Once a year, the general inspection, the following items, to confirm whether it is normal, in order to prevent accidents during stamping production process, it is best to replace them regularly.

• Important relays.
• Electrical pressed components such as micro switches with high operating frequency.
• operation button, emergency stop button (usually used)

4.3.5, Other maintenance matters for custom metal stamping parts quality

• In addition to the mechanical and electrical  sheet metal stamping parts inspection methods of the general machine tools mentioned above, if there are special additional devices (such as air cushions, mechanical feeding, etc.), they should be inspected regularly.
• The electrical parts are most afraid of dust and oil. It is absolutely impossible to open or remove the door.
• Replace the metal stamped parts and pay attention to the fixing, and after the test, you must first test the operation, and then confirm that there is no problem, the machine can work.
• If the machine is used frequently, the time for checking the interval should be shortened, especially the clutch components and special attention.
• The manufacturer of each electrical component has a description of its life. In actual use, attention should be paid to the frequency of work and the working environment. Check and replace it frequently to avoid accidents. The Project life:
  1. Electromagnetic switch Motor life is 500,000 times (or one year)
  2. Auxiliary electric cymbal Mechanical life 500,000 times (or one year)
  3. Push button switch 5 million times (or one year)
  4. Micro switch 20 million times (or two years)
  5. Counter 5 million times (or two years)
  6. Solenoid valve 3 million times (or one year)
     (The above metal stamping  service life, each manufacturer is different, for reference only)
• The rotary cam switch has been adjusted before leaving the factory, please do not adjust it arbitrarily.

Surface treatment of stamping parts:
Plating (zinc, cadmium, copper, chromium, tin, nickel, gold, silver, etc.), electrostatic spraying, painting, electrophoresis, screen printing, etc.

One of the most extensive is electroplating, at the same time relatively common spray, spray paint, blackening, electrophoresis, galvanized, nickel plating.

5.1 Electroplating of stamping parts

Coating metal or other insoluble materials as an anode, the workpiece to be plated as a cathode, coating metal cation on the surface of the workpiece to be reduced to form a coating. In order to eliminate the interference of other cations and make the coating uniform and firm, need to use the solution containing metal cations coating electroplating solution, in order to keep the concentration of metal cations coating unchanged.

Electroplating can change the surface property or size of the base material, enhance the corrosion resistance of the metal (coating metal used corrosion resistant metal), increase hardness, prevent abrasion, improve electrical conductivity, lubrication, heat resistance and surface finish.

5.2 Electrophoresis of stamping parts

Electrophoresis is the application of voltage at the Cathode and Anode, the coating ions with charge move to the cathode, and the surface of the cathode produces alkaline interaction to form insoluble substances, deposition on the surface of the stamping parts.

Features:

• The surface is plump, uniform, flat, smooth.
• The hardness, adhesion, corrosion resistance, impact and permeability of electrophoretic paint film are better than other coating processes.

5.3 Blackening of metal stamping parts

The surface of steel stamping parts blackening treatment (or called blue), the principle is to quickly oxidize the surface of stamping parts, forming a dense oxidation film protection layer, improve the rust resistance of steel parts.

Common methods of blackening treatment are: alkaline heating blackening and room temperature blackening.

5.4 Galvanized stamping parts

Zinc plating (Tin) is the coating of zinc on the surface of metals (and alloys) or other materials.

Can play a beautiful, rust and other functions, now the main method is hot.

5.5 Phosphating the metal stamping parts surface

Phosphating is a process of chemical and electrochemical reactions to form phosphate films (phosphating films).

The main purposes of phosphating are:

• Provide protection to the base metal, can prevent the metal from being corroded to a certain extent;
• Used as primer before painting to provide adhesion and corrosion resistance of paint film;
• It is used for friction reduction and lubrication in cold metal processing

5.6 Beneft of powder coating on stamping parts

Powder coating is the use of pressure or electrostatic force to paint or powder attached to the surface of the stamping parts.

It mainly plays the role of anti-corrosion and exterior decoration.

5.7 Baking varnish process

Spray paint on the front and back of the stamping parts, each time the painting is dried by dust-free constant temperature baking room.

5.8 Surface passivation of deep drawing parts

Passivation is the formation of a very thin, dense and strong passivation film on the metal surface. This film exists independently and is usually a compound of oxidized metals.

The passivation film plays the role of completely separating the metal from the corrosive medium, preventing the contact between the metal and the corrosive medium, so as to achieve the role of anti-corrosion.

6.1 Automobile stamping parts mainly includes:

• Automobile structure parts
• Automobile function parts
• Automobile lathe parts
• Automobile relays
• …

6.2 Electronic stamping parts mainly include:

• Connecting devices
• Connectors
• Brush parts
• Electrical terminals
• Elastic parts
• …

6.3 Home appliance components mainly include:

• Electrical components, such as color tube gun parts,
• Small household appliance parts, all kinds of structural and functional parts,

6.4 IC lead frame mainly includes:

• Discrete device lead frame
• Lead frame
• …

6.5 Motor core mainly includes:

• Single-phase series motor core
• Single-phase domestic motor core
• Single-phase covered pole motor core
• Permanent magnet dc motor core
• Industrial motor core
• Mold stator core
• …

6.6 Transformer stamping parts mainly include:

• E-type transformer core
• EI transformer core
• I transformer core
• Other transformer iron chips
• Etc.

6.7 Heat exchanger fins mainly include:

• Industrial heat exchanger fin
• Domestic heat exchanger fin
• Automobile heat exchanger fin
• …

6.8 Other stamping parts mainly include:

• Instrument parts
• IT parts
• Acoustic and video components
• Modern office parts
• And daily hardware
• …

7.1 Roughness of metal parts surface

The process of machining parts, tools, chip nodules and scales will cause uneven size of the surface of the workpiece Pits(contour valleys) and bumps(contour peaks). These bumps and bumps are very small and can only be seen when magnified.

This microscopic geometric feature is called surface roughness.

7.1.1 Surface roughness grade table of stamping parts

7.1.2 How to measure the stamping parts surface roughness

• Comparison
  

  Roughness contrast card of sheet metal stamping blocks

  It is often used to measure the surface of medium or rough parts in the workshop.Determine the measured surface roughness value by comparing the surface of the part with the roughness sample marked with a certain number

• Tracer Needle
  
  

  Surface Roughness Tester

  Use a curvature radius of 2 microns Diamond Stylus to glide slowly along the measured surface. The upper and lower displacements of the stylus are converted into electrical signals. After amplification, filtering and calculation, the numerical value or the contour curve of the measured section are indicated by the display instrument.In general,

  The measuring tool that only displays the surface roughness value is called the surface roughness measuring instrument.

  A surface roughness profilometer is used to record a surface profile.

  Both of these measuring tools have electronic computing circuits or computers, which can automatically calculate the contour arithmetic mean deviation Ra, micro roughness height Rz at 10, contour maximum height Ry and other evaluation parameters, with high measuring efficiency, suitable for measuring the surface roughness Ra of 0.025 ~ 6.3 micron.

7.1.3 Common parameters for roughness:

3types codes and Numbers of RaRzRy are used to represent the data of the roughness meter result diagram.

There are corresponding surface quality requirements in mechanical drawings generally, and the surface whose roughness Ra<0.8um is called mirror surface.

Ra: Mean deviation in contour arithmetic.

Within the sampling length L, The arithmetic mean of the absolute value of the offset distance

Rz: Microscopic irregularity of ten sample points

Within the sampling length l, the average height of 5 maximum contour peaks and the average depth of 5 maximum contour valleys are summed

Ry: Maximum height difference of the profile

Within the sampling length L, the distance between the contour peak line and the contour bottom line

7.2 The main effect of surface roughness on parts

1. Abrasion performance
   The rougher the surface, the smaller the effective contact area between the surfaces, the higher the pressure, the greater the friction resistance, the faster the wear.
2. Clearance fit
   For clearance fit, the rougher the surface, the more easy to wear, so that the working process of clearance gradually increased;
   For interference fit, the actual effective interference is reduced and the connection strength is reduced due to squeezing micro convex peak during assembly.
3. Fatigue resistance
   There are large troughs on the surface of rough parts, which are sensitive to stress concentration like sharp notch and crack, thus affecting the fatigue strength of parts.
4. Corrosion resistance
   Rough parts surface, easy to make corrosive gas or liquid through the surface of the micro concave valley into the metal inner layer, causing surface corrosion.
5. Airtightness
   Rough surfaces do not fit well together, and gases or liquids leak through gaps between contact surfaces.
6. Contact stiffness
   Contact stiffness is the ability of the joint surface to resist contact deformation under external force. The stiffness of the machine depends largely on the contact stiffness between the parts.
7. Measurement accuracy residual
   The surface roughness of the measured surface of the part and the measured surface of the measuring tool will directly affect the measuring accuracy, especially in the precise measurement.
8. In addition,
   The coating surface roughness of the parts, thermal conductivity and contact resistance, reflection ability and radiation properties, liquid and gas flow resistance, conductor surface current flow will have different degrees of influence.

7.3 How to improve the surface finish

7.3.1 Second corresponding processes

Adding polishing, grinding, scraping, rolling and other processes can improve the smoothness and precision of most middle-large metal parts like stamping parts

In addition, ultrasonic rolling technology combined with metal plastic fluidity can improve the roughness of 2-3 grades, and improve the comprehensive properties of materials.

7.3.2 Improve the original process

1. Reasonable Cutting Speed “V”
   When processing plastic materials, such as medium and low carbon steel, lower cutting speed is easy to produce scale, medium speed is easy to form chip nodules, which will increase the roughness.
   Avoid this velocity region and the surface roughness will decrease. So constantly creating conditions to improve the cutting speed, has been an important direction to improve the level of technology.
2. Reasonable supply.
   The size of feed directly affects the surface roughness of the workpiece. In general, the smaller the feed, the smaller the surface roughness, the smoother the surface of the workpiece.
3. Reasonable cutter geometry.
   Increasing the tool front Angle, the extrusion deformation and friction of the material are reduced, and the total cutting resistance is reduced, which is beneficial to chip removal.
   Reducing the friction and extrusion between the back surface of the cutter and the processed surface and the transition surface is beneficial to reduce the roughness of the surface.
   Increasing the radius r of tool tip arc. The surface roughness can also be reduced by reducing the tool’s secondary deflection Angle Kr, the surface roughness can be also reduced.
4. Reasonable material cutter.
   Choose a tool with good thermal conductivity, can transfer heat in a timely manner, reduce the deformation of the cutting area. In addition, the tool should have good chemical properties, prevent the generation of affinity, resulting in the accumulation of chip tumor and scale thorn, so that the surface roughness is too large. You can coat a layer of hard alloy or ceramic materials on the cutting tool surface. When cutting, the formation of oxidation protective film, reduce the friction coefficient with the machining surface, is conducive to improve the surface finish.
5. Improve the performance of workpiece materials.
   The ductility of material determines its plasticity, and the possibility of plastic deformation is high if the ductility is good. The greater the plasticity of the material, the greater the surface roughness of the parts.
6. Select the right cutting fluid.
   Cutting fluid has cooling, lubrication, chip removal and cleaning functions, the correct cutting fluid can reduce the friction between the workpiece, tool and chip, take away a lot of cutting heat, reduce the temperature of the cutting area.
   At the same time, it is necessary to remove fine chips manually and timely or automatically.

8.1 Characteristics of semi-automatic stamping production

• Simple operation, but frequent and repeated.
• High efficiency, the energy consumption of employees is high.
• High working frequency and speed. Easy to produce mental fatigue, resulting in misoperation.
  
• The workload is large, and the production of some stamping parts has a high demand on workers’ strength.
• Generally, semi-automatic stamping production needs to start and operate the equipment with feet or hands, and even manually insert the tool into the die area to carry out the loading and unloading operation.
  Therefore, safety accidents may occur in the process of stamping production.

8.2 Causes and prevention of stamping safety accidents

8.2.1 Stamping accident causes

External element

• The device malfunctioned while the hand was entering the work area
• Workshop temperature discomfort, noise, human influence and other working environment factors, resulting in staff misoperation or even illegal operation
• Mold press is not firm
• The target production volume is too high, the employees work overtime and other production reasons, and the employees don’t have enough rest

Employees factors

• Employee’s behavior of holding tools is not standard
• Multiple operators, but the lack of unified command, action coordination leading to the accident
• Employees violate operating rules and take risks
• Frequent monotonous action, mental fatigue, the staff misoperatio

8.2.2 How to prevent the mechanical damage of stamping

1. Before the operation, carefully check whether the control system is flexible and firm.
   Pay special attention to whether the spring breaks or fails.
2. Do not place the material, test the machine, check whether the operation is normal, confirm there is no delay or continuous punching punch phenomenon, check the integrity of the safety device and effect.
3. Appropriate safty tools must be worn and used during feeding and unloading operations.
4. In the process of operation, if the machine is found abnormal operation, such as abnormal sound, continuous impact phenomenon, electrical fault, should be immediately shut down, check and repair the machine.
5. During operation, inspection, repair, adjustment, cleaning and other operations cannot be carried out.
   You should stop the machine before doing these operations.
6. At the end of the operation, turn off the power, then clean up, tidy up and other work.

8.3 Process and step analysis of semi-automatic stamping

8.3.1 Stamping process of stamping parts manual production

1. Feeding.  Feed the plate into the mold
2. Set the material.  Fix the plate in the mold
3. Take out.  Take out the stamped workpiece
4. Clear waste.  Clear stamping scrap and scrap in mould
5. Operating equipment.  Control stamping equipment for next operation
6. Material transfer.  Move the workpiece out of the workshop

8.3.2 Step analysis of semi-automatic manufacturing of stamping parts

1. Feeding
   The operation is carried out before the slider enters the danger zone. If the plate is put into the mold by hand, it is of great danger.
2. Set the material
   The moment at which the slider is about to move after feeding.
   The way of material ordering directly affects the safety of operation. The more difficult, the longer of the danger time.
   The main way to determine the material is: retaining post bolt, positioning plate, guide plate, guide pin, side knife.
3. Take out
   During slider return trip.Main note: try to avoid manual parts, prevent the occurrence of continuous impact, do not accidentally touch the switch or button. Methods: blanking, elastic unloading, pushing, hand tongs.
4. Clear waste
   Waste is inevitable in the separation process, if not cleaned in time, will affect the operation, damage the workpiece or even scrap the workpiece.
   The power supply or emergency shutdown button must be pressed when cleaning the mold.
5. Operating equipment
   -Push button switch
   Single operation requires self – adjustment of stamping worker to avoid mental fatigue.
   If need multiple operators, you need a unified command or you need to develop a tacit understanding between operators.
   -Foot switch
   Easy to operate, but pay attention to the coordination of hands and feet.
   Do not work continuously for more than 1 hour, relax properly, adjust the state of hands and feet, avoid mistakes.
6. Material transfer
   The workpiece may be finished with sharp edges and burrs, which may cause injuries such as scratches, cuts, stabbings, etc.
   When transferring the moving parts, employees need to wear safety protective equipment and do not directly touch the workpiece.

In recent years, China government has continuously introduced compulsory regulations on energy saving and emission reduction and improvement of Automobile body collision safety. Hot stamping metal technology of ultra-high-strength steel has been used as one of the important ways to reduce vehicle weight and improve body collision safety. Has been widely used. This article introduces the principle, application and process of hot metal stamping technology, and discusses the production line planning of hot stamping workshop.

Hot metal stamping forming principle

Hot stamping technology is a part processing method. First, the billet is heated to a certain temperature, and then quickly transferred to the mold. High-speed stamping and pressure quenching are performed to obtain the required shape. At the same time, ultra-high-strength steel with uniform martensite structure is obtained. Components. The hot stamping technology can be divided into direct hot stamping and indirect hot stamping according to whether the sheet has been cold-formed pre-formed before being sent to the heating furnace.

In recent years, with the continuous maturation of hot stamping forming technology, the number of hot stamping production lines used in China’s automotive industry has continued to rise, and there are nearly 50 hot stamping production lines that have been completed in China. In 2015, China’s passenger car sales were about 23 million units. If more than ten parts such as the A-pillar, B-pillar, four door bumpers, and some chassis parts of each vehicle are gradually changed to thermoformed parts, eventually one Market demand for approximately 230 million thermoformed parts. To meet this market demand in the future, at least 100 hot stamping production lines are needed. Therefore, the hot stamping production line still has a large market and business opportunities.

Application of hot stamping technology in automobile industries

Hot stamping technology is widely used in the United States, Germany, France, Sweden, Japan and other countries. It is highly recognized by the automotive industry. It can effectively reduce vehicle weight, improve collision performance and reduce body manufacturing costs. At present, there are more applications of hot-formed parts for joint-venture brand cars and less for self-owned brand cars, but most of the newly developed models contain hot-formed parts.

Hot forming technology is mainly used on automobile body structural parts to prevent intrusive damage during collisions and ensure living space; the shape is complicated, and the cold forming dimensional accuracy is difficult to guarantee, or multiple pieces are connected, and the overall manufacturing cannot be achieved.

At present, more than 10% of hot stamped parts are used in Volkswagen series. The new VolvoXC90 II is the model with the most hot-formed parts. The hot-formed boron steel used in this model accounts for 40% of the total body weight. The entire cage-type safety body where the driver and occupant are located is built by it. NCAP’s collision score was five stars and it scored high.

Hot stamping process introduction

Hot stamping process

According to whether there is plating on the surface of the sheet, the hot forming process can be divided into hot stamping of plated sheet and hot stamping of bare sheet. The hot stamping process of the plate is uncoiling blanking → sheet heating → hot pressing, quenching → shot blasting → laser cutting.

Hot stamping technology type

The types of hot stamping technologies include thermoforming of equal-thickness and strength plates, thermoforming of laser tailor-welded plates, thermoforming of rolled differential plates, thermoforming of patch plates, and thermoforming of variable thickness plates of equal thickness. Currently, thermoforming of equal-thickness and equal-strength plates is commonly used, and laser tailor-welded plates, rolled differential plates, patch plates, and equal-thickness variable-strength plates are gradually being promoted and applied.

TWB (Tailor Welded Blanks) uses laser welding technology to weld metal sheets of different thicknesses and different materials together, and then press to produce various parts. Different thicknesses can be achieved in different parts of the same sheet , Strength, and its weight reduction effect can reach 20% compared with conventional sheets of equal thickness. Because TWB can be spliced as needed, it has great flexibility. However, there is a sudden change in thickness at the splicing position of the sheet, which makes springback prediction, mold design and manufacturing, and welding seam movement control new topics; and the material hardening caused by the welding seam affects subsequent forming, making TWB unsuitable Formed exterior body panels. In addition, laser tailored welded plates have high requirements on the quality of welds, and cracking of welds is also one of the factors affecting the yield of tailored welded plates.

The Tailor-Rolled Blanks (TRB) are obtained by flexible rolling with a rolling mill. During the rolling process, the roll thickness control system (hydraulic AGC) of the specially designed rolling mill is used to control the position of the rolls so that the pitch can be adjusted and changed in real time, so that the rolled sheet is in the rolling direction of the steel plate. Pre-customized variable thickness distribution

In terms of part production and manufacturing process, the TRB process operation is basically the same as that of ordinary equal-thickness sheet material, which can be produced continuously and has high production efficiency. And the transition area is smooth connected, which is simpler than the design of a mold with a sudden change in the thickness of the tailor-welded plate. In terms of cost, compared to TWB boards with multiple welds, TRB boards have a clear competitive advantage. However, because the sheet of TRB technology is only a single material grade, the flexibility of the shape of the parts is not enough. At the same time, because the entire sheet is rolled, the steel plates of different materials cannot be stitched together.

Patch sheet thermoforming can locally patch parts as needed to improve the local performance of the part. Equal-thickness variable-strength sheet thermoforming can achieve different strengths in different parts of the same part, and there is no change in thickness of the sheet. Compared with laser tailor-welded sheets and rolled thick plates, the blanking cost is lower, but the weight reduction effect is not as good as laser Tailor-welded plates and rolled plates.

Analysis of the advantages and disadvantages of hot stamping technology

Compared with traditional cold stamping, hot stamping has obvious technical advantages, and its advantages are mainly reflected in 4 aspects: ⑴ hot stamping can obtain ultra-high strength parts, the thickness of the parts is relatively small; improve the collision performance of the body, and achieve the body’s Effective weight reduction; ⑵ relatively good formability of parts, small internal stress, almost no rebound, high dimensional accuracy; ⑶ small forming force required for hot stamping, small requirements for press tonnage, in most cases, 800t high speed The hydraulic press can meet the hot stamping needs of most body parts; The simple design of the body structure effectively reduces the number of sheets; through the optimized design of the body structure, the comprehensive manufacturing cost of the body-in-white is effectively controlled.

Of course, the shortcomings of the hot stamping technology itself are also relatively obvious, mainly: ⑴ slow production cycle; ⑵ the unplated plate stamping process will produce oxide scale, which needs to be cleaned regularly; ⑶ the cost of hot forming mold itself is high, parts need to be heated, follow-up Laser cutting is also used, so the manufacturing cost of the part is relatively high. Therefore, when designing a new model or improving a model, it is necessary to reduce the thickness of parts or reduce the number of reinforcing plates to control the overall manufacturing cost of the body-in-white; the working environment is relatively poor compared to cold stamping.

We also proposed a five-point solution to the optimization of hot stamping process: ⑴ common mode solution. From 1 die out of 2 pieces to 1 die out of 4 pieces, the later goal is 1 die out of 6 pieces or even higher. Reduce mold cost and improve production efficiency. Trimming scheme after thermoforming. Trimming punching dies replace laser cutting tooling, which can increase production cycle time and reduce laser cutting costs. (3) On the part product side, design the hot forming die positioning process hole, and the laser cutting fixture to locate the process hole. ⑷For non-functional trimming lines, the position tolerance is defined as ± 2mm. ⑸ can use blanking to replace laser cutting.

Hot stamping production line planning

Hot stamping production Capacity planning

Taking the hot-formed parts of 24 supply units as an example, after the process is optimized, only 8 sets of molds need to be opened, and the calculation is based on one hot-forming production line.

The annual capacity calculation is based on an average of 25 working days per month, 2 shifts per day, 8 hours per shift, and an average of 4.2 strokes per minute. The total number of strokes per year is: 4.2 × 60 × 8 × 2 × 25 × 12 ≈1.2 million strokes.

The hot forming production line planning requires 24 supply units. Each unit requires 8 punches to calculate the production load. The first stage invests in one hot forming production line; the latter stage invests in the second stage to build a second production line according to the needs of market development.

Hot stamping company Plant planning

According to the first and later stage investment plans, the thermoforming workshop (including auxiliary buildings) needs 5760m2 (120m × 48m) to meet production needs. If you add an unwinding and blanking line, you need to add a 30-meter span

Hot stamping factory Public power

The installed capacity of the whole line is 1500 ～ 2000kW, among which the power installation capacity requirement of the press is about 500kW. The protective gas of the heating furnace requires a nitrogen generator. Compressed air for loading or unloading by robot or linear system is 60m3 / h. The production line cooling system is divided into two parts, one is the cooling of the press itself; the other is the mold cooling system. If the entire equipment cooling system is based on the principle of one reserve and one reserve, the installed power of the cooling system is close to 500kW.

Hot stamping manufacturer technology Concluding remarks

The hot forming technology of ultra-high-strength steel has shown great potential in reducing body weight, improving safety performance and dimensional accuracy, and has broad application prospects in the automotive field. The implementation of the thermoforming process is a systematic project involving multiple specialties: materials, forming, automation, and laser processing. How to reduce the energy consumption in the entire process, improve the performance of parts, ensure the quality stability and consistency of parts, Is the focus of the development of thermoforming processes.