Cutting Extruded Acrylic-direction? Effects?

[Larry Bratton]

Some extruded acrylic has indicator arrows on the mask showing the direction of extrusion. Does anyone know how the produced product is effected if laser cut across the direction of extrusion in lieu of with the extrusion direction? I am wondering if it would cause more crazing when glued with solvent cement? What happens when it is bent with a heat bender? Could it cause twisting or warping? Your input is appreciated.

[Vaughan Raymond]

This seems to be a common question. I've worked in aerospace manufacturing for a few years and after all acrylic machining drilling forming etc. it must be annealed or it will craze for sure.

Below is an excerpt from a major aerospace mfgrs. process specs.

5.5.1.1 Anneal acrylic plastic parts which have been drilled, cut, formed, routed or machined,
after all such operations have been completed.

5.5.1.2 Anneal acrylic plastic parts that are to be cemented after drilling, forming, routing or

machining, both before and after cementing. Anneal all acrylic plastic parts at a temperature of
160 ± 15°F for 24 to 48 hours, followed by air cooling to room temperature.

[Doug Griffith]

When we vacuum form, extrusion direction affects shrinkage with some materials. More in one axis than the other. I doubt it affects laser cutting at all.

[Larry Bratton]

This seems to be a common question. I've worked in aerospace manufacturing for a few years and after all acrylic machining drilling forming etc. it must be annealed or it will craze for sure.

Below is an excerpt from a major aerospace mfgrs. process specs.

5.5.1.1 Anneal acrylic plastic parts which have been drilled, cut, formed, routed or machined,
after all such operations have been completed.

5.5.1.2 Anneal acrylic plastic parts that are to be cemented after drilling, forming, routing or

machining, both before and after cementing. Anneal all acrylic plastic parts at a temperature of
160 ± 15°F for 24 to 48 hours, followed by air cooling to room temperature.

Yep..told my wife I was taking over her oven for a couple of days to anneal acrylic before I glued it up....she said..OK..but no oven..no food. So, I reckon that's the name of that tune, no annealing taking place here. (actually I was aware of that but my question is "does it make any difference if you cut in the extrusion direction or across)

[Dan Hintz]

The cut itself won't make any appreciable difference, but the annealing process will (at least for extruded)... you will get the greatest change in dimension along the axis of extrusion. So, if you have a project with a somewhat critical dimension, you want that dimension perpendicular to the axis of extrusion.