I recently got some laser cut POM sheets, 2mm thick, they are also know as acetal (sold as Delrin, Celcon, Ramtal, Duracon,
Kepital and Hostaform) and many other names, I see it being discussed under various brand names more than POM.
Basically the sheets are bent, they don’t sit flat, and I need them to sit flat on a flat surface.
So now I am curious why these are not flat compared to others that are flat from another source?
Did the supplier used bent sheets as material for the laser cutting or did the weather affect them, like they was transported in
freezing temps of around –5C (23F) then probably moved to like other higher temps and so on. They are quite small actually around 30cm (1ft)
To me this looks like the supplier just used some non-flat POM sheet for the laser cutting, but I am not sure, could the
transportation have caused them to bend? They are pretty tough and if flexed they bounce back right how they were instantly, which is one of the reasons I like POM actually, I mean the material is pretty tough.
Anyone got experience with POM sheets? I am not even sure what is going on and weather to make any more orders or not with the same supplier.
Often times with certain plastics sheets are sheared off from a large solid round much in the same way a wood veneer is made. From my experience this material always has a bit of a bend to it.
I suppose it could be possible to relieve the stress by heating.
This is what Dupont has to say about annealing POM “Annealing should be performed in air or in inert mineral oils at160 ± 3°C (320°F), for 30 minutes + 5 minutes per mm of wall thickness. Overheating and hot spots should be avoided, and parts should neither contact each other nor the walls of the oven/bath. Parts should be left in the oven to cool slowly until 80°C(176°F) is reached.
It was some 3day quick shipping from shipping from inside Europe by UPS, nobody should imagine weeks of bending and pressure from China, or something like that.
Then I would conclude that they laser cut some warped sheets to begin with, because they were packed well, to me it looks quite hard for them to warp during a quick shipping.
I just can’t pay a relatively high price for laser cut parts then try to flatten them myself with controlled temp in an oven.
Many years ago, around the turn of the century, I worked for a company that processed glass for windows and other uses. The company was sold many years ago after becoming a supplier of Anderson patio doors (thanks to the impression I made loading glass into the washer during the inspection in negotiation ). Before leaving due to a rotator cuff injury and pinched nerve in my neck I ran cnc “v-groove” machines that cut patterns into glass sheets.While most people may think glass is flat, there is often major deviations. Plastics are more deformable and if a sheet is clamped down for cutting the final product may exhibit unexpected deformation (to the end user) due to stresses in yhe sheet and thermal effect of the cutting process.
Yeah, the thing is that some other sources will not come/send warped sheets, so maybe better cutting techniques, better sheets to begin with, I don’t know.
I like their easy and detailed user interface online, but yeah the results are not so great for these 2mm thick sheets, lots of details but then the entire sheets are warped.
). Before leaving due to a rotator cuff injury and pinched nerve in my neck I ran cnc “v-groove” machines that cut patterns into glass sheets.While most people may think glass is flat, there is often major deviations. Plastics are more deformable and if a sheet is clamped down for cutting the final product may exhibit unexpected deformation (to the end user) due to stresses in yhe sheet and thermal effect of the cutting process.