Tech Tip Tuesday: Odd Form Printing

Pad printing is known to be a method for odd form printing.  Each part’s shape and topography pose its own set of complexities with getting print in the area you wish to see it and a one to one representation of the image you are attempting to print.  That is to say, the curvier the part, the more likely you are to encounter distortion of the image.

As a general rule of thumb, present the print area of the part as perpendicular to the stroke of the pad (Z axis) as is possible.  This will combat “skid” of the pad on initial contact.  As the pad “reaches” or stretches over the part … so goes the image.  The best method by which to combat the distortion is to have a pad that is as big as the machine will allow.  Oversized, if you will.

Depending on whether the curve can be considered complex (the part falling off to different degrees in many angles) it may be necessary to appropriately size the image, bring it down, or pre-distort the artwork to compensate for the stretch.

The inkjet equipment is not as forgiving with parts that are not flat.  The manufacturers prescribed distance of the array to the substrate is anywhere between 1mm – 3mm depending on the type of print head.  The answer then … if the substrate will be any further than the prescribed distance … it is not flat enough.

That said, we have come up with work arounds to where we can jet ink up to approximately 10mm.  These tricks include manipulating drive voltages and size of dot to be jetted.  The image quality will certainly suffer when you start to range outside of the 1 – 3mm range but the end user is left to discern whether the quality is acceptable.