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Soft Touch

Safety Features

Unitrol Soft Touch Safety Features - Production Engineering

  • Protects against PINCH POINT INJURIES with a fully PASSIVE system
  • Installs on most spot welder controls, including ENTRON
  • SAVES MONEY by improving weld Quality

We are pleased to offer the new Unitrol SOFT TOUCH welder safety option. This patent pending function keeps the electrode force very low until it is safe to apply full welding force. This passive fail safe system has been approved by OSHA in manufacturing plants nationwide. 

It is standard on the 9180 Unitrol controls series without extra cost. Existing Unitrol controls can be upgraded for this SOFT TOUCH function. It also installs on the entire ENTRON family of controls.

How it works: After initiation, electrodes start to close under low force. A Unitrol touch sensor system decides when the electrodes have closed on or near the metal being welded. If an obstruction is detected prior to closing, the electrodes will go back to the fully opened position. No adjustment of SOFT TOUCH is needed when changing welding force or electrode spacing.

The system is field adjusted (with lockable settings) so that force between electrodes in the advance portion of the stroke remains low enough to avoid major injury to the operator’s fingers. For press welders, this will even reduce force between electrodes to considerably less than the dead weight of the ram.

Fail safe system: If the sensor switch is already closed when the welder is being initiated, the electrode will not even start to move, and the display will show which sensor input is closed at that time. If the sensor wires from the SOFT TOUCH system have become disconnected or are making poor contact, the electrodes will close under low force and then return after a short field-settable delay (1-99 cycles).

What hardware is needed: To make this system operate, you will have to add a 5-way externally piloted solenoid valve, a shuttle valve, and a precision pressure regulator system to an existing 4-way externally piloted (or direct acting) solenoid valve. Unitrol offers three kits for easy installation:

Heavy Rams: Kit #9181-34W is used on:

  • Press welders that have dead weight (with air disconnected from welder) of over 50 pounds. The kit is factory pre-plumbed for fast installation and includes all necessary components and interconnecting tubing.

Light Rams: Kit #9181-34Y is used on:

  • Press welders - that have dead weight (with air disconnected from welder) that is less than 50 pounds, or does not drop by its own weight.
  • Rocker arm welders - the kit is factory pre-plumbed for fast installation and includes all necessary components and interconnecting tubing.

Light Weight Gravity Drop Rams: The #9181-34H kit is used on:

  • Press Welders that have dead weight (with air disconnected from welder) of less than 50 pounds and drops smoothly by gravity. The kit is factory pre-plumbed for fast installation and includes all necessary components and interconnecting tubing.

Redundant sensor: You can also add your own proximity switch or LVD system adjusted to close a switch when the electrodes are less than ¼” apart to the system. The SOLUTION will not turn on the high-pressure valve until both METAL is detected and the proximity switch has been closed. This is often useful for applications where the parts being welded are not flat prior to the weld.