4 trouble shooting tt 2009

©2008 Mate Precision Tooling1

Trouble Shooting

©2008 Mate Precision Tooling

Troubleshooting

Customer Generated

Tooling Problems

Troubleshooting

Customer Generated

Tooling Problems


• Broken or cracked punches, strippers and dies

• Galling

• Misalignment of punch and die

• Slug pulling

• Stripping problems

• Lock ring damage

• Broken or worn punch springs

The Most Common Customer Generated Tooling Problems:The Most Common Customer Generated Tooling Problems:


• Incorrect die clearance

• Incorrect sharpening methods

• Lack of tool maintenance

• Lack of sheet lubrication

• Tool size or station is not suited to the application

• Wear in the machine’s tool holder or keyway is causing alignment problems

• Tool holder in the machine is not adjusted properly, resulting in alignment problems

The Most Common Causes Of Tooling Problems:

The Most Common Causes Of Tooling Problems:


• Right tool for the job (size and clearance)

• Are punch and die sharp ?

• Any wear on keys and alignment rings ?

• Orientation of punch and die in turret is correct ?

Operator ChecklistOperator Checklist


Broken and Damaged PointsBroken and Damaged Points

CAUSES:

• Incorrect die clearance

• Incorrect sharpening method

• Galling (too much heat)

• Not punching deep enough into the die (slug build-up in die)

• Point size too small relative to material thickness

• Incorrect punch/die alignment

• Slug pulling

• Camber in the sheet

• No corner radii on punch corners

chipped


Cracked Punch TipCracked Punch TipCustomer did not sharpen properly. The decreased shear depth increased the flats. This caused the punch to crack due to excessive load on the punch cantilever.

Hair line crack

Flats increased by bad grinding practices

Use correct shear geometry or move to larger station.

Cantilever


Sharpening ProblemsSharpening Problems

•Undressed Wheel (black marks)

•Lack of Coolant

•Excessive Material Removal

•Wrong Grinding Wheel Choice


When punching in a Finn-Power D- Upforming Station, the maximum Ø of the slug is reduced from 78 to 53 mm !

Maximum slugMaximum slug


Part produced with correctly resharpened die


Part produced with incorrectly resharpened die


Debris between punch and punch driver or overtightening of draw bold can cause failure (see catalog for Nm)

Broken Punch RetainerBroken Punch Retainer


Broken StrippersBroken Strippers

• Look for indications on the stripper face that it has been hit, or for unusual marks or indentations.(e.g. slug on top of sheat)

• Also inspect the inside of the stripper for damage if none is evident on the outside surface.(punch ground off too much)


Broken StrippersBroken Strippers

Punch radius may hit stripper if the SBR is too short. This will cause the stripper to break.


Stripper maintenanceStripper maintenance

Remove debris in stripper – it may cause guide damage, sheet marking, etc.


Causes:

• Uneven support of die in machine - dirt, debris or damaged shims under die

• Incorrect sharpening method

• Lack of corner radius

• Standard duty tool used in heavy-duty application

• Unnecessary keyways on slitting tools used in auto-index

Broken or Cracked DiesBroken or Cracked Dies


Crossed Punch and DieCrossed Punch and Die

• Severe damage to sheet, tooling, and machine may result from crossed punch and die.

• Operator should always visually or physically check tool orientation after installing tooling in the turret.


Tool damage caused by poor storage or

handling

Tool damage caused by poor storage or

handling

• Dents, dings and scrapes can cause turret damage and damage to other tool components.

• Handle precision tooling carefully and store each item in a separate location to promote maximum tool life.


Broken Die AdaptersBroken Die Adapters

10 ton maximum limitation for all die adapters that step down one station.


Galled PunchesGalled Punches

Galled Punches cause:

• Stripping problems

• Poor hole quality

• Accelerated tool wear

Excessive heat, incorrect die clearance and lack of lubrication are the most common causes

Galling (build-up) can be cleaned right after the job is finished (when it is still “warm”)

Cold Galling can sometimes be removed. Nitride treated or Maxima coated punches should be considered. Reduce machine ram speed. Use sheet lubrication and check die clearance.


Misalignment-PunchesMisalignment-Punches

Uneven punch surface wear on any one side of the tool (marking and or galling).

More evident on long, narrow shapes but can happen on any shape or size tool.


Misalignment of DiesMisalignment of Dies

Damaged side has marks and abrasion, evidence of being hit.

Undamaged side is sharp and has no evidence of being hit.


Misalignment Indicator : ”Rat tail”

slug


Sharpening ProblemsSharpening Problems

Wave pattern on the die surface indicates a grinding wheel that has not been dressed properly.

This causes heat that changes the metallurgy of the material and accelerates tool wear.Coolant and correct coolant mix ratios must be used.

Dress wheel frequently to prevent heat checking . Check grinding wheel for proper hardness and grain size.


Damaged die shims Damaged die shims

Die shims need to be replaced when damaged and need to be made from hardened shim stock or purchased from Mate.


Lock Ring DamageLock Ring Damage

Damage to locating key and lock ring keyway are caused by incorrect tool loading procedure. To prevent this damage, lower punch assembly slowly into turret using T-handle tool.

Damaged locating key in machine can cause guide damage.


Spring MaintenanceSpring Maintenance

Note: Springs have a finite life and require maintenance. Be aware of the different types of springs used in Mate’s various tooling styles.


Broken Disc SpringsBroken Disc Springs• Disc springs require

lubrication with EP grease.

• Stripping problems and spring sleeve damage can occur if springs are not maintained.

• If one disc spring is broken replace the entire stack.

• Maintain proper spring count and stack pattern.


Application ProblemsApplication ProblemsCracked Spring retainer

12.7mm (1/2”) thick material exceeds tool design limits


Application Problem: Clamp and Form Clearing Fully Guided AssembliesUse only insert style punches with clamp clearing strippers, or punch will hit stripper.


Punching in tough material like Hot Rolled Steel ?

Following a monitored case at a Finn-Power customer.

After following this program the customer achieved

much better quality and remarcable extension of tool life.

Punching tough material


MAINTENANCE INSTRUCTIONS FOR D-ULTRA FULLY GUIDED SLITTING TOOL (5x85) . USED FOR MATERIAL 3mm HOT ROLLED STEEL Generally: Air blow to max (just the air) Big rooftop shear on the punch, ~ 4 deg Use of a gas spring Big total clearance on stripper, ~ 0,2mm Big die clearance, D/C 0,9 Nitreat treatment or Maxima coating could be tried Needed maintenance at every time: Remove galling from the punch every time when sharpening or more

frequently, if possible Check the condition of the stripper opening => maintain or replace Clean all the tooling parts with degreasing liquid like PRO 2011 tai PRO 2010

(WWW.PROSPECT.NL) or with some other imilar liquid Clean the stripper pocket of the guide really properly from all dirt and particles Clean the stripper surface, coming into the pocket really properly Put oil on each part before assembling Check the fit between the the punch tip and the stripper opening Install the stripper very carefully. The stripper should slide into its pocket with

little or no mechanical assistance. It may be necessary to tap the stripper into place very gently, by use of a brass bar . This way it is secured that surfaces are fit to each other before installing the screws

Allways Install NEW screws M4x 12 Torque settting for the stripper screws is 5,5Nm. Use loctite when installing

the screws Once a week: Cleaning of auto-index station Every second month: Replace all the keys: Auto-index station and the tool


Stripping forcesStripping forces


Avoid problems: Preventive maintenance

Avoid problems: Preventive maintenance

Remove punching debris from inside of guides, strippers and punches.


Trouble shooting summaryTrouble shooting summary

4 trouble shooting tt 2009

Documents

tool damage

punch springs

die surface

size tool

tool wear

resharpened die

broken die adapters

crossed punch