Top 10 Die Protection Tips

Good die protection is essential to a successful stamping operation. The purpose of die protection is to stop the press before damage occurs. Here are 10 of the top tips to help you prevent die damage.

1. Know the “critical angle”. The critical angle is the last point in the press cycle where an E-stop can stop the ram before the die closes. You should know the critical angle for every die in every press that can run it. If you have a Wintriss SmartPAC, determining the critical angle is easy – see the following link for easy instructions: https://www.wintriss.com/wcg/knowledgebase/10111.html
2. Know when to top stop. Your die protection control should be set to E-stop the press for virtually every die-threatening circumstance. However,  when the monitored event occurs past the critical angle, top stop is a better choice. The only thing worse than crashing a die is crashing a die and sticking the press on the bottom.
3. Eliminate “nuisance stops”. A nuisance stop is a press stoppage initiated by a sensor when no real problem exists. These are often caused by sensors that require adjustment during set-up. Repeated nuisance stops encourage operators to ignore die protection or turn it off.
4. Know your feed tolerance (and use it). Don’t make feed detection too precise – this will likely cause nuisance stops. Your pilots can align the strip if the feed is not perfect.
5. Get the feed moving. Give your die protection a chance to work – get the feed started as soon as the pilots have cleared on the upstroke. Using a programmable limit switch to program feed advance makes this easy.
6. Use infrared only for part ejection. Sometimes, a blast of air will carry some lube out of the die, tricking a visible light sensor into thinking the part came out. Infrared sensors are much less susceptible to oil in the sensing field.
7. Use a diffuse sensor “screen” to detect part ejection. When a single sensor may not cover enough area to detect when air-ejected parts fly out of a die on an unpredictable trajectory, you can “stack” diffuse reflective sensors, wiring them in parallel to a single control unit, to increase the detection area.
8. Mount sensors to avoid rewiring. More sensors are damaged during handling than during use, so make sure to install sensors so they don’t have to be removed during routine die maintenance. Run sensor wires/cables in a channel or protective sleeve to prevent breakage.
9. Use die-mounted junction boxes. The single most important thing you can do to preserve your sensors is to us a die-mounted junction box. Cable damage is the most frequent cause of sensor replacement, but press-mounted junction boxes force you to keep long lengths of cable coiled up on the dies. Click here for sensor interface and connection hardware.
10. Avoid these common mistakes: using sensors without bench testing first; using sensors that need adjustments; forgetting about the environment where the sensor will be installed; using one type of sensor for every application; trying to use sensors that don’t meet the electrical requirements of the control.

Good die protection is within your reach. Read Wintriss Control Group’s “50 Tips for Better Die Protection” presentation to learn more.

And be sure to contact Production Resources for assistance with the die protection your stamping operation demands.