Walker Magnetics IMI Smart-D Series, Operation Manual

800-WMAGNET

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4.1.4 Workpiece Material

Low carbon steel such as SAE 1020 steel, are nearly as good conductors of magnetic lines of force as pure iron. 

However, many other alloys contain non-magnetic materials which reduce the ability of magnetic lines of force to flow. An 

alloy such as SAE 300 series stainless steel is almost as poor a conductor of magnetic lines of force as air. 
Type 416 stainless steel is considered magnetic, but it contains enough chromium so that a magnet can develop only 

about one half as much magnetic force as it can on an SAE 1020 steel workpiece. Also, because of the carbon content, 

the force developed on typical cast iron is less than one half that developed on SAE 1020 steel. (Chilled cast iron further 

reduces the force to less than one quarter.) 
Additional concerns regarding Magnetic Holding should be forwarded to O. S. Walker, Inc.

4.2 Full Holding

(Green Push-Button)
In the Full holding position, full output voltage is supplied from the control to the chuck as soon as this function is 

selected. The indicator light for the Full holding position is illuminated when this function is selected.

NOTE: Full holding has equivalent holding force to 100% on the Variable holding control knob.

4.3 Variable Holding

(White Push-Button)
When the operator presses the Variable holding button, the output voltage of the control can be adjusted from zero to full with 

the Variable control knob.
A varying amount of Residual hold can be achieved by turning the Variable control knob to zero from its previous holding 

position without pressing the Residual button.

4.4 Residual Holding

The output of the control is reduced to zero when this function is selected. The control turns the chuck fully ON for a short 

period of time, thus leaving a recognizable residual holding power in the chuck; this is called True Residual. During this brief 

pulse, the indicator light, will be ON until another function is selected.

4.5 Release

Selecting the Release function initiates an automatic release cycle. During the release cycle, the output voltage produced 

by the control is reduced from full to zero in a predetermined number of equal pulses (see Figure 4 1). The polarity of these 

pulses alternately reverses from negative to positive as the magnitude of the voltage decreases. The SMART-D can generate 

a maximum of sixteen pulses per release cycle, but is set at the factory for eight.
The Release indicator light will flash ON and OFF to show that release is taking place, and will remain ON when the cycle is 

complete.
The duration of each pulse is automatically controlled. The time between pulses is automatically adjusted by the control for 

the optimum Release cycle time.
The SMART-D has an external and internal adjustment for the number of pulses per Release cycle. This adjustment allows 

the operator to select the number of pulses it takes to get the fastest, most complete release of a part.