Wish I'd Paid More Attention!

How would you know? Ask an engineer. Ask her what the difference is between "requirements" and "legal requirements" if you are unsure.

Best regards, Spehro Pefhany

You're an idiot.

my

FYI everyone - I am sifting through all these great replies, but have not had time these past few days to really concentrate on them. I will get to it shortly - but this is a fascinating topic that looks to have tentacles everywhere.

On the surface, it really looks like there's only so far an EE can go with this until he must employ the services of a plastics expert.(?) There's just too much to know - unless we're just talking a few one- off's for a proof-of-concept, or rough prototype. Which really, is probably where I'm at anyway -- but the widget seems so simple, I was hopeing to get further along...

-mpm

The 3-D proto machine will print your one-offs, no problem, and they will be strong enough or even stronger than what you choose for your final piece(s).

You can even have molds made, and pour (inject) your own parts with advanced modern epoxies. A little in-house cold injection molding, as it were. Rubber molds allow removal of all remnants after cure.

technicians.https://na.dmecompany.com/MoreInformation/images/MC/Sect5/recycle_ins...

I took several Plastics Technology classes decades ago. Check college Industrial Technology departments, college bookstores, etc.

Doing fiberglass layup probably won't help. Rotational blow molding probably won't help. Polyurethane form filling probably won't help. Plexiglass (perspex in UK) there's a bunch of tricks using finer and finer sandpaper down to really fine wet or dry in water and then buffing or flame polishing (edges) Thermoplastic and Thermoset plastics? Injection molding DIES can be an expensive PITA to get made correctly, (draft, shrinkage) Great if you anticipate huge quantity production.

In the 1980's micro milling machines that hook up to PC's came on the market but the one I saw was only for soft materials like plastic or wax, fell into use for carving false teeth and in a more refined form carving glasses lenses.

They came up with a process for thermoset or vinyl dispersion where 3D objects can be knitted at the point where two crossed laser beams intersect.

In recent years the hobby groups called Makers came up with a little milling machine on a shoestring budget capable of milling most of the parts to replicate build another unit like itself.

If you use polystyrene for prototyping you can use model airplane glue to chemically bond scraps together with rectangular gussets or little blocks to hold right angles together.

Remote controls, keyboard keys, computer and monitor cases are probably ABS.

Truthfully, It's more likely picking a material that meets the need for strength, toughness or flexibility, and not designing your own polymer chain chemistry.

Pretty near every consumer electronics case is made out of injection molded ABS.

If you're not handling fluids you probably don't even care about microporosity.

There WAS a chemical issue to do with plastics in the last 2 years, biphenyls. To make plastics that are squishy and flexible like rubber they were using this added chemical but it turned out to be highly toxic. (Was in baby bottle nipples) I heard it also won't age well after 20 years.

Tell me why you would not go with a stock injection molded ABS material like almost every other consumer electronics widget.

We've come a long way since billiard balls and acetate collar stiffeners, but the advice to copy what others do is not as bad as it might sound.

mpm, Look at what was used for similar products and think about what properties the particular plastic has.

Gripe away, Archie! LOL

Pretty comprehensive summary Spef.

Probably the most constructive help you're going to get is from the part vendor in the quotation process, if you can manage to be taken seriously.

They will be interested in your CAD drawing of the proposed part, your material expectations and intended manufacturing scale / time frame. Simple is good.

A serious response will include a drawing, turned around with suggestions for manufacturability and cost, suggested commodity materials that would best suite internal current proposed processes, and tooling cost estimate alternatives for different schedules of manufacturing.

Some estimates may offer to eat tooling for a pre-fixed scale volume, tied to an expected tool life and the associated finishing and handling costs of the associated part. Unless you're planning to buy the tool outright, this may be the best way to go.

Like all manufacturing processes nowadays, there will be off-shore options for both tooling and actual part fab.

RL

No shit.

The 3D printers out there now print directly, there is no need for intersecting laser curing sessions.

You draw it, and you print it. You send the CAM work over to the metal shop and they'll mill one out for you. The printed unit looks exactly like the metal one.

Not a lot different for the plastic targeted item.

Go here for industrial quality polymer selections and suggestions: