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Trouble Shooting. Troubleshooting Customer Generated Tooling Problems. The Most Common 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.
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Troubleshooting Customer Generated Tooling Problems
The Most Common 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 Causes Of 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
Operator Checklist • 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 ?
Broken 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
Customer 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 Cracked Punch Tip Flats increased by bad grinding practices Cantilever Use correct shear geometry or move to larger station.
Sharpening Problems • Undressed Wheel (black marks) • Lack of Coolant • Excessive Material Removal • Wrong Grinding Wheel Choice
Maximum slug When punching in a Finn-Power D- Upforming Station, the maximum Ø of the slug is reduced from 78 to 53 mm !
Broken Punch Retainer Debris between punch and punch driver or overtightening of draw bold can cause failure (see catalog for Nm)
Broken 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 Strippers Punch radius may hit stripper if the SBR is too short. This will cause the stripper to break.
Stripper maintenance Remove debris in stripper – it may cause guide damage, sheet marking, etc.
Broken or Cracked Dies • 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
Crossed 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 • 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 Adapters 10 ton maximum limitation for all die adapters that step down one station.
Galled Punches Excessive heat, incorrect die clearance and lack of lubrication are the most common causes • Galled Punches cause: • Stripping problems • Poor hole quality • Accelerated tool wear 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-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 Dies Damaged side has marks and abrasion, evidence of being hit. Undamaged side is sharp and has no evidence of being hit.
Sharpening 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 Die shims need to be replaced when damaged and need to be made from hardened shim stock or purchased from Mate.
Lock Ring Damage Damaged locating key in machine can cause guide 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.
Spring 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 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 Problems Cracked Spring retainer 12.7mm (1/2”) thick material exceeds tool design limits
Application Problem: Clamp and Form Clearing Fully Guided Assemblies Use only insert style punches with clamp clearing strippers, or punch will hit stripper.
Punching tough material 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.
Avoid problems: Preventive maintenance Remove punching debris from inside of guides, strippers and punches.
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