Thread: Plastic molding on a budget?

There are new SLA (stereo lithography), SLS (selective laser sintering) and deposit based methods which have come a long way in the last 2 years. Again, the catch is you need CAD and reverse engineering of the original object if you want to make a new one. It's easy to do if you have a 3d scanner and the software though

The printing cost is all determined by how much raw material is used. You can even color the object so when completed it just needs clear coating for protection.

Originally Posted by shadow0000

2. Blow Molding: Blow molding is like injection molding except that hot liquid plastic pours out of a barrel vertically in a molten tube.

5. Gas Assist Molding: Also called gas injection molding is used to create plastic parts with hollow interiors. Partial shot of plastic is then followed by high-pressure gas to fill the mold cavity with plastic.

Actually, blow molding is more like gas assist molding. A cylinder of plastic is extruded and descends between the parts of a mold; the mold closes and air is injected into the cavity to force the cylinder out to conform to the chilled mold. It's the way a lot of pails and bottles are formed.

Originally Posted by ik632

There are new SLA (stereo lithography), SLS (selective laser sintering) and deposit based methods which have come a long way in the last 2 years. Again, the catch is you need CAD and reverse engineering of the original object if you want to make a new one. It's easy to do if you have a 3d scanner and the software though

The printing cost is all determined by how much raw material is used. You can even color the object so when completed it just needs clear coating for protection.

These SLA and SLS systems are really coming along. They're relatively slow (although that's likely to change), and are probably best -- right now, anyway -- for low-production uses and prototyping. That makes them absolutely perfect for the sort of work we do in carPCs because almost everything we do is a single unit or a very small number of units.

ik632 -- it appears that you're working in this area; what's your take on this?

Between SLA and SLS it's a tough call. I actually called a friend today to have him send me samples of the different materials that you can use. There's a new PP and ABS for SLS that looks promising for parts for the car. The materials for SLA are good as well and there's a PP and ABS like material as well. The specs for the materials used in SLA and SLS are pretty close so it would come down to the surface finish. I think the SLA might be a little smoother but I can't say for sure before I see the samples.

As far as speed goes I'm not all that worried about it. Anything that we're going to do would be completed in one shift. You could technically have it started at the beginning of a shift and shipped that same day so if you're really in a rush you'd end up paying for making the shop move the schedule around. I know a few places that I work with that will do pretty much any rapid prototyping type of print. I just need to send them an STL of the model.

There's one material that is used in both the SLA and SLS that feels like PE at certain thicknesses, like PP in others, and like ABS in others yet. I think that material has some flexibility and comes in black. I hope that I like the way it feels because the specs make it sound just about perfect for the car applications. The temp range would even handle the cold and hot.

We recieved some samples a couple months back that had different strengths. Easy to hard on the flexability. Ours started a yellow/orange clear plastic. But currently we have a cheaper manilla color plastic.

The top of SLA parts are really smooth. The bottom will be bumpy due to the way the SLA machine builds up the plastic. It needs supports to build onto so you get a honeycomb support structure. Once the part is done the supports can be removed and the part cleaned. However, for our carputer applications the part will probably still need a little sanding and finish paint.

So FYI: if you have a part made this way and you want one side smooth make sure you let them know to build it with that side up. If its a curved surface you will still need to sand it even.

check my older post of a bezel made with SLA
S-10 Install,In progress,baby steps,first rip apart dash :)

I'm always used plastic molded materials. For curiosity is there a parts in making plastic molding which include the operation of automated insert molding production cells for high volume low cost production of sub-assemblies? Maybe Technology is one of the core values that make an area of precision molding which many customers recognize.

Originally Posted by Mike38

I'm always used plastic molded materials. For curiosity is there a parts in making plastic molding which include the operation of automated insert molding production cells for high volume low cost production of sub-assemblies? Maybe Technology is one of the core values that make an area of precision molding which many customers recognize.

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Rapid prototyping

Have you seen the printers that have multi durometer materials? You typically have a white and black (one is really soft and one is hard) and then when you print they can make a mix of 100-0 to 0-100 of the two. It still has a support mechanism so you really have 3 canisters in the machine. Curing is done with UV light. I have their brochure sitting on my desk as I talked to the guy a few weeks ago. Stuff looked pretty good. Much better quality than FDM and about similar to SLA. Also, more durable than epoxy/sand, but you can't really do much more than gray scale, so you are stuck with sand if you want color for architecture.

I've been vacuum forming protoype parts with styrene.Then I coat the styrene with polymer clay...."Magic Sculpt" to make parts.
I made my vacuum former from a desk drawer and Peg board.
I live in San Francisco Bay area and my favorite store is http://www.tapplastics.com
Tap Plastics demo's can also be seen on youtube.
There is an Oregon store near you