Re: Tooling

From: Steve Deak (ht-grp@gs1.cinti.net)
Date: Mon Aug 12 1996 - 23:26:23 EEST


Paul J. Wehner wrote:
>
> Hello Steve,
>
> I was just wondering if you might elaborate on your reasons for
> steering away from cooling channels and infiltration. Is it based on
> a desire to "simplify" the tooling {aka. eliminate steps… those
> occurring prior to prototype production, such as cooling channel
> implementation, as well as those taking place afterward (infiltration)}?
>
> Also, would you mind commenting on what kind of accuracy you
> expect out of your SL tooling? What are the major tooling factors for
> Hasbro…accuracy, surface finish, timeliness, cost?
>
> Just trying to get a feel for what your looking to achieve with your
> rapid tooling applications. We’ve seen some encouraging results from
> conforming cooling channels, tool coatings, and various backings, but
> we might not be on the same page (right now) if your looking for one
> stop tool production.
>
> Any chance you’ll "show your cards"?
>
> Thanks in advance,
>
> Paul J. Wehner
> Fraunhofer USA
>
> ---------------------------------------------------------------
> From: Steve Deak[SMTP:ht-grp@gs1.cinti.net
> Does anyone use SLS composite nylon or Tru-form for injection mold
> tooling? I am using SL epoxy ACES molds and would like to know if the
> higher heat deflection temperatures of SLS materials are of benefit for
> prototype injection molds.
>
> I'm making small lot sizes( <20 pieces; polypropylene, ABS, styrene, etc)
> with good results from the SL tools but would like to look into other RP
> tool methods. I would like to avoid internal water line cooling.
> Additionally, I am interested in avoiding metal tooling which may require
> copper infiltration/heat treat.
> ---------------------------------------------------------------
>
> Steve Deak E-mail: ht-grp@cinti.net
> Manager-RP Services Voice: (513) 579-3270
> Hasbro Toy Group Fax: (513) 579-3250
> 615 Elsinore Place
> Cincinnati, OH 45202 "Our Business is Fun!"
> USA

Paul:

Typical injection mold materials include Styrene, Polypropylene, ABS,etc.
 Most are not reinforced and need impact resistance and flexibility.
Further, Hasbro is VERY good at creating low volume aluminum tools, fast,
 for initial part runs. Aluminum tools are conservative and low risk (we
know they will produce parts and they are relatively durable).

My task is to put a material correct part in the hands of the engineer
as soon as possible. If RP tooling is to be viable for producing
these initial parts, it must be faster and lower in cost than aluminum
tools. I give here on surface finish, however. We are talking
prototypes.

Elimination of cooling lines and ejector pins is one way to reduce cost
of the tool. Typically part runs are complete before gating and shutoffs
are worked out. Flash is not generally a problem for <50 pieces.

Building direct RP injection molds has been done here at Hasbro with good
results. Still, RP tools are risky in so much as if I dress-up an RP
tool (cooling, inserts, polish, etc) Murphy's 3rd Law of Fracture
Mechanics says the press operator will crack the tool on the first shot.

I want tools I don't have to do much with other than lightly finish and
shoot. If the parts work, great! But, typically design changes on
good parts soon follow. Assessing risk, we then make an aluminum tool or
make another RP tool.

In the prototype stage, tolerances vary dramatically. I'm looking for
the best I can get, but reality says some dimensions are +/- .005" while
most dimensions are +/-.020" (However our engineers think everything
needs to be +/- .0005"!). These are PROTOTYPES! We're dealing with
injected materials which shrink .020"/", non uniform shrink is everywhere
(this may be one of the issues we're working out). Heat treat or copper
infiltration for RP metal tools right now requires technical expertise
and induces additional tolerance/warpage if not done properly.

I need to simplify my life.

-- 
Steve Deak			E-mail: ht-grp@cinti.net
Manager-RP Services		Voice:	(513) 579-3270
Hasbro Toy Group		Fax:	(513) 579-3250
615 Elsinore Place
Cincinnati, OH  45202		"Our Business is Fun!"
USA



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