I am working on a product much smaller than I normally work on and overall depth of product is key. What is the minimum wall thickness I can work to for a small (mobile phone sized) ABS product. I have worked to 1.5 as mimum before but we want to go down to 1mm locally in some places is this too thin? The part will have a work life similar to a mobile phone. Also we have a colured part being bonded as a decal on top of this in ABS also, could I go down to 0.5mm for this as it will carry no load in itself?
Going below 1 mm would make me nervous, but that is without knowing anything about the design.
Before you cut metal for a mold, I would have a machine shop mill 3-4 models of your design from ABS. This will give you the closest approximation of the material properties. Determine testing to represent real-world use scenerios (e.g. 4-foot drop test, etc.), and see what wall thickness should be the minimum.
For the “decal”, I am currently doing one at 0.25 mm. But again, without knowing your design, I could be comparing apples to oranges.
From my experience even 1mm is a challenge. At that thickness you are going to have a lot of potential for cosmetic and molding issues. We tried this and had to go back up to 1.2 nominal to avoid several issues.
Like was mentioned though, this is really going to depend on your material (does it have to be ABS? PC or other resins may work better with the thin wall) and what cosmetic and physical characteristics you need (a .5mm product may be thinner but if it shatters on drop that won’t be good).
.5 is very thin - but without seeing the design perhaps theres a way to get away with it. Is there a reason you can’t use a thinner decal or possibly an IMD instead?
I think using too thin ABS will make the product feel not solid enough. If you are not bound to ABS, there was a service of 3M, that coated plastics with a advanced metallic alloy, improving their properties greatly. I do not know if they still do it.
Hi,
I recently detailed a keyfob device that sounds similar. with a 0.5 decal on the top surface. I ended up using a ABS+PC blend with a nominal wall thickness of 1.4mm (with a 1mm TPE overmould in some areas) and a large 0.5mm decal.
I got away with 0.5 degrees draft on internal ribs and details as the product was quite shallow and highly polished. 0.5mm T for ribs worked without causing sink issues and the exterioe walls were cut down locally to 0.4mm in a couple of places for snaps and I got away with it.
every product is different though and a few CNC abs prototypes were used for testing, and the tool took some tuning to work well, but i echo what others have said, thin walls feel cheap and nasty and will likely have flow issues on something the size of a mobile phone. try to beef it up from 1mm.
on a side note all the mobile phones I;ve pulled apart have based their structure on internal pressed metal components with very thin exterior mouldings that function like cladding. if you can’t get thicker walls on your mouldings this approach could save you some space (at a cost of course)
Out of curiosity, are you using ABS because of its low radio frequency attenuation as in cell phones? If your constraints are purely geometric, would die cast magnesium suite your needs? The material is much stronger and can be cast with walls as thin as .5mm in some cases.
I recently did a phone case that was a co molded PC with TPE. In one of the sections, the PC got down in the .5 mm range, and even with the TPE on the other side of it, it warped quite a bit. I ended up needing to thicken up that part. Granted this was PC and not ABS, I’m guessing that you’ll run into issues under 1mm.
0.5mm is pretty thin, but I would think the TPE may have exacerbated the problem rather than try to prevent it. When it cools and contracts it exerts a load on the substrate that can cause the kind of warping you’re talking about. You could thicken up the whole part, reduce amount of overmold, add ribs, etc.
Bayer does a lot with high pressure formed HPF, backprinted Makrolon materials for cell phones. FIM Film Insert Molding with injected backup in places of higher impact or mechanical connections.