How to Set Up a Continuous Mold?

Progressive die stamping workshop

Before setting up the die

① Choose a suitable punching machine for the tonnage of the die and check whether the height of the die is within the permissible range of the punching machine.

② The lower table of the punching machine should be cleaned, and there should be no foreign objects. The bottom surface of the lower die holder of the die should not have any debris and should be placed flat.

③ The mould should be placed in the middle of the punching table.

④ The stroke of the punching machine should be selected in inch movement.

Table of Contents

In racking the die

① When pressing the die, raise the ram first and then slowly lower it to the lower dead point by inching.

② For moulds with die handles, the die handle must be aligned with the die handle hole to the lower dead centre, and the lower die must be closed and retracted first.

③ For moulds without handles, place the mould in a suitable position and be careful not to block the drop hole for moulds with drop holes.

④ The cushion used must be flat and checked to ensure that it is balanced and that it is not blocked to prevent damage to the mould.

⑤ The mould can be formed by tightening the upper mould, then putting in a scrap of the required thickness, using the slider to adjust it to a suitable closing height, and hitting it empty two or three times before locking the lower mould.

⑥When setting up a V-shaped die, close and lock the upper and lower die sliders and then raise the slider to the size of the thickness of the material to be punched

 

After setting up the die

① Check that the upper and lower dies are not locked.

② Check the upper and lower dies for any abnormalities.

③ Put the tools in place and clean up the site.

Code of practice for the use of stamping dies

1.Before using the die, check against the process card whether the die used is accurate and consistent with the process card.

2.The operator should understand the performance of the die and master the correct operation method for using it.

3.Check whether the moulds used are in good condition and whether the stamping materials meet the requirements of the process drawings to prevent mould damage due to raw materials not meeting the requirements.

4.Check whether the equipment used meets the process requirements, such as the stroke of the press, the tonnage of the press, etc., are compatible with the moulds used.

5.Before installing the mould, wipe the machine table, slider and the upper and lower surfaces of the mould clean of oil, dust and other debris.

6.Check whether the moulds are correctly installed on the press, whether the upper and lower mould bodies are fastened to the press, and whether the moulds are installed with the correct closing height and avoid eccentric loads as far as possible. When adjusting the closing height, use the manual pointing method to adjust the stroke depth gradually and forbid even turning before confirming the adjustment.

7.After the mould is installed, check whether the fastening screws of the mould installation base are locked correctly to avoid damage to the mould and machine tool. Correctly use the safety protection and control devices on the equipment, and prohibit storing any items not related to production on the working table while processing the workpiece. During the work process, the mould must be checked regularly and adjusted in time if there is any loosening or slipping.

8.Strictly implement the workshop “three checks” system. Use moulds in processing the first few pieces of products should be carefully checked according to the process card drawings, the first piece of qualified before mass production.

9.When two or more people are working, there must be a person in charge and responsible for the operation of the foot pedal device.

10.The height of the mould and the height adjustment of the machine need to use the pad iron can only be placed under the mould under the template; we need to pad on the upper template, which needs to be agreed upon by the technical staff, under the guidance.

11. mould in use, to comply with the rules of operation, in the operation of the equipment, it is forbidden to reach into the mould to pick and place parts and remove the residual material; in the operation of the foot switch, the action of the hands and feet should be coordinated, refill or take parts, feet should leave the foot switch. The hand or foot must leave the button or pedal whenever a workpiece is punched to prevent misoperation.

12.Check the mould operation at any time during the working process and carry out maintenance and repair when abnormalities are found.

13.To lubricate the workpiece’s surface and the mould’s active parts in time.

14.After the mould is used, the mould should be unloaded from the press correctly according to the operating procedures, and when dismantling the mould, it must be done in the closed state. Clean up the work site and respond to the technical staff in time for any problems arising during mould use.

15.To clean the surface of the dismantled moulds, remove oil, dust and other debris, to achieve a clean appearance, no rust, no grease, small tooling on the shelves, large tooling designated storage place to place, placed neatly. Do the lubrication work to ensure the tooling is in good condition, and the tooling storage area should be equipped with storage signs.

16.The handling and lifting of moulds should be done properly, slowly and slowly.

17.If the operator does not operate according to the operating procedures and causes damage to the process equipment, the management will be assessed according to the workshop economic responsibility system.

Cautions

(1) Before installation and use of the mould, strict inspection should be carried out to remove dirt and check whether the guide sleeve and the mould are well lubricated.

(2) Regularly check the turntable of the punching machine and the die installation base to ensure the coaxial accuracy of the upper and lower turntables.

(3) Install the convex and concave die on the turntable according to the die installation procedure, ensuring that the convex and concave dies are oriented in the same direction, especially for dies with directional requirements (non-circular and square). More care should be taken to prevent wrong or reverse installation.

(4) When the edges of a punch press’s convex and concave dies are worn, they should be stopped and sharpened in time. Otherwise, they will rapidly expand the degree of wear of the die edges and accelerate the wear of the die, reducing the quality of the punched parts and the life of the die.

(5) Stamping personnel should use soft metals (e.g. copper, aluminium, etc.) to prevent damage to the die when knocking or smashing during the installation process.

(6) The moulds should be handled lightly during transportation and should never be thrown around to avoid damaging the edges and guides of the moulds.

(7) To ensure the service life of the die, the spring of the die should also be replaced regularly to prevent fatigue damage to the spring from affecting the use of the die.  

Surface grinding machine

Daily maintenance of stamping dies

The daily maintenance of the mould is carried out by the operator and confirmed by the mould maintenance personnel. The maintenance cycle is 1 time/batch; the mould operator will record the condition of the mould in production, the quality of the first and last parts and the process parts, the implementation of maintenance and the maintenance situation in the “Mould Daily Maintenance Record” table after the parts have been made, as a basis for whether the mould needs maintenance.

Checking the mould before use

(1) Check whether the mould identification is intact and clear and whether the mould used is correct against the process documents.

(2)Check whether the mould is complete, whether there are cracks in the convex and concave moulds, whether there are knocks and deformations, whether the screws in the visible part are loose and whether the edges are sharp (punching and cutting moulds), etc.

(3) Checking that the upper and lower templates and working table are clean and that there is no lubricant between the guide pillar and guide bush.

(4) check that the raw materials used are consistent with the process documentation to prevent damage to the moulds and equipment using unqualified raw materials.

(5) Check that the machine tool is reasonably equipped with the mould.

(6) Check whether the mould is correctly installed on the machine tool and whether the upper and lower bolts are tightened.

Checking during the use of the moulds

1.Before adjusting the mould, check whether there are any foreign objects inside and outside the mould, whether the fixed screws of the edge are loose, whether the plate material used is clean and clean

2.Check that there are no foreign objects on the operating site, whether the ground is neat and tidy, and that there are no factors affecting safe operation.

3.The forming die on the open tiltable press should be adjusted for press force and press force, and whether the guide pins are correct and complete.

4.The first part of the mould after the trial production is checked according to the sample and judged to be qualified by the quality inspector before mass production.

5.During the use of the mould, the operating rules should be strictly observed, the surface of the working parts and the movable mating surface of the mould should be surface lubricated at regular intervals, and the waste should be cleared in time.

6.During the work, check the working condition of the mould at any time, stop immediately when abnormal phenomena are found, and notify the team leader with the shift to determine the treatment plan.

Checking of moulds after use

1.after the use of the mould, use the machine tool to open the mould cavity, use the tool to hold the slider on the machine tool, under the premise of ensuring safety, clean up the cavity, check whether the cavity surface is damaged, whether the guide pillar guide sleeve is loose, check whether the pressure material, receding material mechanism and the edge is intact, check whether the positioning parts are correct and reliable, check whether the visible fasteners are loose; apply oil to the guide slip and working surface.

2.Clean and oil the mould mounting surface to prevent rust.

3.Remove the mould from the machine tool; lifting should be proper, with a slow start and release.

4.When changing the moulds for the frame longitudinal beam forming, the working surface inside the mould base cavity should be cleaned, and the mould base cavity, the edge and the adjustment block should be checked for damage. The removed modules should be placed gently in the designated position in the order, wiped and oiled to prevent rusting.

5.Select the unpieces after the mould is to be discontinued for a full inspection.

6.Fill in the technical status of the moulds on the “Mould Daily Maintenance Record” form after the inspection is completed, send the qualified ones to the designated storage place in time and intact, and send the unqualified ones to the mould maintenance workshop.

Analysis of mould defects and measures to solve them

The convex die wears too fast

①The mould gap is small. Generally, it is recommended that the total mould gap is 20% to 25% of the material plate thickness.

② Bad alignment of the convex and concave moulds, including the mould base, guiding components, and turret inlays, due to lack of precision, etc.

③The temperature of the convex die is too high, mainly due to overheating the punch caused by the same die stamping for a long time.

④Inappropriate die sharpening methods, resulting in annealing of the die and increased wear.

⑤ When one-sided local punching, such as step punching, punching angle or shearing, the lateral force will cause the punch to deviate to one side, and the clearance on that side will be reduced, resulting in serious wear of the die. If the machine tool dies are not installed with high precision, the punch will seriously deviate over the lower die, damaging the convex and concave dies.

Die with material problem

①The sharpness of the die edge, the larger the rounding of the edge, the easier it is to cause waste rebound.

②The amount of mould entry and the amount of mould entry for each station of the machine tool is certain; the small amount of mould entry will easily cause the scrap to bounce.

③The clearance of the mould is reasonable; if the mould clearance is not suitable, it is easy to cause the scrap rebound.

④Whether there is more oil on the surface of the sheet being processed.

⑤ Spring fatigue damage.

Methods to prevent mould banding.

1.Use special anti-banding concave moulds.

2.Moulds should be sharpened regularly and demagnetised.

3.Increase the clearance of concave moulds.

4.Use bevelled edge moulds instead of flat edge moulds.

5.Install rewinders in moulds.

6. Increase the mould entry volume reasonably.

7.Check the fatigue strength of the mould spring or unloading sleeve.

Die alignment problem

In use, the die is prone to different amounts of wear and tear on each side of the core, with some parts having larger scratches and faster wear, which is especially obvious on the narrow rectangular die. The main causes of the problem are.

①Insufficient design or machining accuracy of the machine tool turret, mainly the poor alignment of the die mounting base of the upper and lower turret.

② The design or machining accuracy of the mould does not meet the requirements.

③Insufficient precision of the guide bush of the mould’s convex die.

④Inappropriate selection of mould clearance.

⑤ Poor alignment of the mould mount or mould guide bush due to wear from long-term use.

To prevent uneven mould wear, the following should be applied.

① Regularly use the alignment mandrel to check and adjust the alignment of the machine tool turret and mounting base.

② Replace the mould guide bush in time and choose a convex and concave mould with suitable clearance.

③Adopt full guide moulds.

④Strengthen the responsibility of the operator and find out the cause in time to avoid greater losses.

Use of special forming moulds

To meet production needs, it is often necessary to use forming or special moulds, mainly bridge-shaped moulds, shutter moulds, countersink-shaped moulds, flip-hole tapping moulds, camber moulds, stretching moulds, combined moulds, etc. Using special or forming moulds can greatly improve production efficiency. Still, the price of forming moulds is higher, usually four to five times that of ordinary moulds. To avoid mistakes, the following principles should be noted and followed.

1. Conduct a direction check when the mould is installed to ensure that the mould is installed in the same direction for both convex and concave dies.

2.Adjust the punching depth of the die correctly according to the requirements, preferably not more than 0.15mm per adjustment.

3.Use a lower punching speed.

4.The sheet should be flat without deformation or warping.

5. The forming process should be positioned as far away from the clamps as possible.

6.Avoid downward forming operations when using forming dies.

7.Punching should be carried out following the common mould first, and the forming mould should be used last.

Judgment of common defects of stamping parts and handling methods and preventive measures

For the outer plate, the requirements are high, and there should be no obvious defects. The inner plate parts should not have cracks or dark cracks. The deep-drawn parts should first check whether the pressure point is clear, then check whether there are dark cracks, then touch them by hand and push them with oil stones.

Causes of scrap production.

A.Poor quality of raw materials

B improper installation and adjustment and use of the punching die.

C the operator not feeding the strip correctly along the positioning or not ensuring that the strip is fed at a certain gap.

D change of clearance or wear of the working and guiding parts of the die due to long-term use.

E loose fastening parts due to prolonged shock and vibration, resulting in a relative change in the mounting position of the die.

F negligence of the operator, not according to the operating procedures.

 

The main measures to prevent scrap.

A Raw materials must be in line with the specified technical conditions (strict inspection of the specifications and grades of raw materials, in the case of conditions for dimensional accuracy and surface quality requirements of the workpiece for laboratory inspection).

B The various aspects specified in the process regulations should be comprehensively and strictly observed.

The press dies and other tooling equipment used should be guaranteed to be in normal working order.

D A strict inspection system is established in the production process. The first part of the press must be fully inspected and put into production only after it has passed the inspection.

E Insist on a civilised production system, e.g. the transfer of workpieces and billets must be carried out with suitable workstations. Otherwise, the surface quality of the workpieces will be affected by crushing and bruising.

F During the stamping process, the cleanliness of the mould cavity must be ensured, and the workplace must be organised in an orderly manner.

Common defects and measures to solve them

1) Convexity and unevenness

Judgement methods: touching by hand, pushing with an oil stone and seeing with the eyes.

Recommended to push with oil stone; the bright spot is convex, dark spot is depressed.

Cause: If the unevenness is found, check whether foreign objects, such as sand grains, are in the mould.

Treatment: If there are sand particles, apply mould-wiping paper to wipe the mould clean.

2) Cracking (dark crack)

Judgment method: check by eye the corner of the deep-drawing parts, such as material deformation of the larger places, which should be turned over the reverse side to check.

Cause: It may be the mould strains, and the crimping force is large.

Treatment: Check whether the workpiece is seriously strained and reduce the crimping force appropriately.

3) Wrinkling

Judgement method: see with your eyes

Cause: Low crimping force

Treatment: Increase the crimping force appropriately.

4)Burr

Judgement method: see with the eyes

Cause: Large gap between the convex and concave moulds.

Treatment: Repair the mould

5) Hole deviation

Judgement method: check on the inspection tool and compare it with sample parts.

Reason: The workpiece is not set up properly, and the mould positioning device is a problem.

Treatment: If the hole still deviates after the workpiece is set correctly, report to the shift manager and inform the mold repair.

6) Less hole

Judgement method: compare with the sample.

Cause: The punch is broken.

Treatment: Stop production immediately and report to the shift manager immediately to inform the die repair.

7) Hole deformation

Judgement method: see by eye.

Cause: Punch wear.

Handling method: Lightly oiled, serious oiling still deformation should be reported to the shift manager and notified to repair the die.

8) Deep drawing is not in place

Judgment method: see if the pressure point is clear.

Cause: The main pressure is small.

Treatment: adjust the main pressure appropriately.

9)Folded edge is not good

Judgement method: compare with sample pieces

Reason: The piece is not set up properly, and positioning device problems.

Treatment: Set up the workpiece properly; if it is still bad, report to the shift manager and inform the mould repair staff to fix it.

10) Embossing

Judgment method: see with the eyes

Reason: There are granular impurities adhering to the working surface of the mould.

Treatment: Wipe the upper die of the mould clean.

11) Strain

Judgement method: see with the eyes

Reason: The working surface of the mould is worn, and the mould is not hard enough.

Treatment: Repair the mould.

12) Grit

Judgement method: push with an oil stone

Reason: The material or mould surface is not clean.

Treatment: Check the material or wipe the mould surface clean.

13) Bump, scratch

Judgment method: Use eyes to see

Cause: The incoming or outgoing material touches the mould and other hard objects.

Treatment: Be careful in and out of the material, hold the product gently and put it away gently, and adjust the closing height of the mould upwards if necess

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