Improve the Press's Stopping Time

The faster the press stops, the more time a die protection system has to detect and react to problems.   In addition to regular brake maintenance, the following things can improve the press’s stopping time:

Quick dump valves on the clutch/brake
A quick dump valve is a low-cost, pneumatically-controlled valve that (as the name implies) is designed to quickly remove the downstream air when the supply air is shut off.   A quick dump valve installed on the clutch/brake assembly of a stamping press will quickly exhaust the air from the clutch when the clutch/brake valve opens.   Many newer air clutches have quick dump valves built in.   Older machines can easily be retrofitted with a quick dump valve.

Properly set counterbalance air pressure
The air counterbalance system on a press is designed to counterbalance the weight of the ram and upper die.   Heavier upper dies need a higher counterbalance pressure.   If the counterbalance pressure is set too low, it can cause, among other things, an increased stopping time on the downstroke of the press.   If it is set too high, the press will take longer to stop on the upstroke.   Optimum stopping time is achieved when the counterbalance pressure is correctly set for each upper die.   The RamPAC module for the Wintriss SmartPAC makes this setting automatically.

Counterbalance Programming Menu

Valves properly sized to the press
OSHA requires that a part-revolution mechanical power press be equipped with a cross-checked control valve commonly called a 'dual safety valve'.   Presses manufactured before the requirements went into effect had to be upgraded with new valves.

Properly set clutch air pressure
Most press manufacturers recommend that the clutch air pressure be set to around 60 PSI.   Unfortunately, many users think that if 60 PSI is good, 80 PSI must be even better.   There is no benefit to using a pressure higher than clutch's design limit.   Using a higher pressure increases the volume of air that must be exhausted from the clutch at disengagement.   More air takes more time to get through the valve, and increases the press's stopping time

Clean or Replace the Muffler on the Clutch/Brake Valve
For the machine to stop, the pressurized air must be removed from the system. The last possible impediment to air evacuation is the muffler on the valve. If it's not there already, this item should be added to the press maintenance schedule.