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Injection molding tooling options

Hi,

We're exploring different packaging configurations for a product. The casing will either be a casting (aluminum, etc.) or injection molded plastic.

For the plastic option, we are concerned as to how much up front effort we should put into the tooling knowing that wear is inevitable, etc.

Volumes are such that hard tooling is the only practical option (~100K pieces/year). But, the question as to whether to budget for tool rework/maintenance vs. simply replacing the tooling on some schedule.

The latter option allows us to plan for packaging changes that might be beneficial (for engineering or cosmetic reasons).

Any folks have a feel for when it makes more sense to just toss the tooling and start fresh? (i.e., after 100K pieces, the tooling doesn't "owe us anything" :> )

Thx,

--don

Reply to
Don Y
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Hi, don:-

There are different grades of plastic tooling. The good stuff will do

1m pieces with minimal maintenance. Skimp on components, raw materials, hardening, etc. and you save some money up front in materials and machining costs, but you might see deterioration after
Reply to
Spehro Pefhany

Yikes! Some research for an earlier project suggested ~10K squirts for cheap tooling, ~100K for better tooling. I dislike getting dragged into packaging issues. Get somebody who's expert in this sort of thing!! :-/

I don't *think* color is an issue. Pick one and that's it. Material choice will be more of a problem. The trouble is balancing look/feel against durability, etc.

No, this will be done domestically. "High value added" design so it can afford the domestic fabrication costs (even the *boards*).

That was my point. If you are already planning for "other models", perhaps just *plan* for the tooling to be discarded and rebuilt for each new generation/model. Instead of budgeting to maintain molds and/or worrying about quality slip as the mold ages.

Reply to
Don Y

..

  1. On interpretation of the SPI numbers.. note that 10,000 is < 100,000. There are certainly ways to get closer to 10k than 100k - just choosing soft materials and nasty plastic is one easy way. Modern machines can cut really nice materials fairly efficiently (EDM doesn't really care). I recently was shown a complex CNC-milled cavity that was almost ready to use without polishing.. milled directly from hardened steel, very tight (micron) tolerances. The "milling machine" wasn't a Harbor Freight special though, it produced dust rather than chips and cost about half a million dollars. In some places you can buy a house for that. EDM can produce hardened parts (even from exotic materials) that fit together so snugly that you can barely see a gap.
  2. I tend to agree with your conclusion, but it's nice to know what questions to ask, particularly if you are the only one with a systems perspective and/or if you have skin in the deal.

--sp

Best regards, Spehro Pefhany

--
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Reply to
Spehro Pefhany

The impression I got, at the time, was that there is a difference, IN PRACTICE, between what can be *claimed* vs. can be *actualized*. I.e., "derate liberally" -- or, end up "watching CAREFULLY!"

Yes, a friend owns a machine shop. He's been systematically replacing all the Bridgeports, etc. with wire EDM machines. I think he has 4 of them, currently.

(But, he specializes in very exotic work... very high piece part prices, etc.)

I think it boils down to "laziness" (bad choice of words but it fits my vocabulary). Easier to pass off a task to someone standing in front of you than it is to go looking for the

*right* person to do the job. (I've had clients ask me to hire staff for them, train them, etc. "Um, what makes you think I *want* to do those sorts of things???!").

And, I can either argue with them expounding on my ignorance of the subject -- or, go through the motions of getting the "low hanging fruit", dropping it in their laps, shrugging my shoulders and saying, "You'll have to figure out how to interpret this and factor it into *YOUR* business decisions..."

I just *really* dread the "doing things over" mindset: "That might make economic sense to *you* but it's not how I want to spend *my* time!" :-/

Reply to
Don Y

Just a wild guess here. I but that some better molding houses have someone on staff that knows just what you need, and the outfit sells this person's time by the hour or as part of a product run. Negotiated up front. Maybe that is a useful way for you to approach this one.

?-)

Reply to
josephkk

IME, once you drag a vendor into a deal, it's hard to push them back *out*. Now, you've got someone *else* injecting their wants, urgency, etc. into a process that is already ripe with those issues. They want to "make the sale happen". I/client want to "gather information". The sale might *never* happen though the vendor doesn't look at that option as objectively as I/client might.

I much prefer getting some education before approaching a vendor with my requirements. Then, let him suggest alternatives and

*reasons* for those alternatives. But, I need to be able to understand and evaluate those alternatives from my/client's perspective: "No, that won't work because..." or "But, isn't a consequence of that ..."

In the past, I've had IE's available to tell me what was possible and the (approx) costs/consequences of each option. So, I could approach vendor candidates with a shopping list and hear their reactions to the alternatives that I am willing to explore ("Gee, why is this guy pushing the low end product so hard? maybe he can't *make* the better product?")

Reply to
Don Y

this

I have seen enough of what you speak of. Just an idea that has worked = for me a couple of times. It is your fish, fry it as you see fit.

?-)

Reply to
josephkk

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