Rework Molded Plastic Part

[Buck61]

Is there a practical machining method or other process that can uniformly remove about .001”-.005" of material consisting of shut-off flash around the rectangular opening [circled in 1st photo attached]? The opening measures .083 +/-.005" high x .177 +/-.005" wide x .110 +/-.005" deep. The part is injection-molded Sabic NX03583 plastic.

The small rectangle openings 2X are located within a larger rectangular feature, measuring 3.30" length X .50” wide x .55" deep, perpendicular to the 3.30” dimension which makes rework very difficult [See 2nd photo w/ Vernier showing 3.30” distance between each of small rectangle openings].

The mating actuator tab [circled 3rd photo] must clear and move through the small rectangular opening. Current production parts features interfere due to excess flash around the rectangular opening from worn "wipe" shutoff in mold tooling 2X.

Rework method/process and setup must be accurate and repeatable as 2800 parts need to be reworked. The 2800 parts represent safety stock to be molded before production mold is taken offline to fix the openings and other OOS spec features.

*No texture. As-molded non-cosmetic internal surface feature per SPI AQ-103.

Thanks,
Buck61

 

[JohnRBaker]

I see no photos...

John R. Baker, P.E. (ret)
EX-Product 'Evangelist'
Irvine, CA
Siemens PLM:
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[3DDave]

For 2800 parts? Pretty tough to deal with. If it was a lot more, then a custom broach would be useful, but I don't know if lead time and cost will allow that. Also, with no photo, I can't see if there is access.

If you do add a photo - don't use any non-alphanumeric characters, except "." as the filetype separator. Popular choices that don't work" "/", "&", "%", "#" <- don't use those.

 

[dgallup]

Flash is usually trimmed with a knife, a manual process with wide variability.

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[Buck61]

I downloaded files for attachment using window at bottom of 'post' form where it says "Attachment" and "Click Here to upload your file to Engineering.com" at bottom of window (shown below) prior to submitting original thread. I noticed after the fact that no photos appeared or attached. I have not posted in a while and not sure how to attach files.

 

[IRstuff]

You didn't follow directions. There's a link that you have to click to insert the uploaded file's URL into the post. The files are not hosted on this site; they're hosted on Engineering.com

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[Buck61]

See respective photos 1 thru 3 below

 

[IRstuff]

Is it on all 4 sides of the opening? Seems to me that something like a dental drill could certainly reach the openings, but alternately, can you rework the mating part instead? What's the fit tolerance required?

TTFN (ta ta for now)
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[Buck61]

From information I was given, all 4 sides. Dental drill is a good suggestion. Unfortunately RW of mating part in this case will impact mating with 3rd part in assy (not shown). No formal fit specified however affected part database tol. schedule for dimensions 0-.49"= +/-.005".

 

[JohnRBaker]

Since you mention the tooling is "worn", perhaps a little refurbishing/reworking is called-for.

John R. Baker, P.E. (ret)
EX-Product 'Evangelist'
Irvine, CA
Siemens PLM:
UG/NX Museum:

The secret of life is not finding someone to live with
It's finding someone you can't live without

 

[Buck61]

Absolutely JohnR. That is the plan as mentioned in the last paragraph of my initial post.

 

[hendersdc]

If I were doing this, I would use a flat needle file and do the work by hand. 2800 parts will take a long time though...at one part/minute you are looking at about 47 hrs of rework.

 

[Pud]

You could try a hot air gun. A brief blast often re-melts the thin flash tothe point it is hardle visible. Takes a bit of trial and error to get the flash off before the thicker section is affected. A second or two will often suffice.

www.tynevalleyplastics.co.uk

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