How to Specify Threads and Inserts on an RFQ
A Helix Is a Shape, Not a Joint
A thread or insert RFQ needs one route per feature: molded thread, molded-in insert, or post-install insert. Add internal or external, class, engagement, insert part number, and who supplies hardware. The CAD helix shows shape. It does not show release path, insert supply, or resin-free crests.
Molded thread, molded-in insert, and post-install insert are three scopes
The STEP shows a helix. It does not show who loads the insert. The solid can show a helical cut or a boss with a hole. It cannot show whether you will unscrew a core, load an insert in the tool, or install hardware after the shot. Write one of those three. If you want the reviewer to pick, write open to DFM on route and still give class and engagement.
Internal molded thread needs a release path
Internal molded thread without a release note is a tooling surprise waiting for review. An external molded thread on a boss can often unscrew or split with the main pull. An internal molded thread needs a release path: an unscrewing device, a collapsing core, or a redesign to an insert. That path is a tooling-scope note. This page does not publish a mechanism menu.
Post-install insert is a scoped secondary, not the mold handles it
Post-install insert installation is a secondary. Molded-in is insert molding. Read secondary operations on an RFQ when hardware goes in after the shot. A molding-only approval does not order inserts.
One hole, one route. Four holes can have four different routes.
Route Each Feature Before You Quote
Molded thread: internal or external, class, engagement
Write molded thread, internal or external, the class you will accept, and engagement as a length or as modeled. Threads as modeled is not a specification. It is a shape with hope attached.
Molded-in insert: insert drawing, material, customer-supplied or sourced
Open insert molding services when the insert sits in the tool during the shot. Write molded-in insert, the part number, and who supplies the hardware. For the customer-insert package, read quote insert molding with customer inserts.
Post-install insert: heat-set or press-in method named on the RFQ
Open post-mold inserts when the hardware goes in after ejection. Write post-install insert and the install method. Do not write insert molding when you mean heat-stake after the shot.
Open to DFM on route, but still give class and engagement
If the team has not picked a route, write open to DFM on route and allow or forbid an insert alternative. Mixed routes on one part are normal. Four post-install inserts and one molded neck thread is a valid list. A single word, threaded, is not.
A worked routing note: Holes 1 to 4, post-install inserts, customer-supplied. Hole 5 unused. Neck, molded external thread. That is routing. See compare page is a reading assignment, not an RFQ field.
What to tell sourcing: pick the route before you treat the number as a hardware plan. Insert supply, incoming checks, and steel scope change with the route. A later switch from molded thread to insert is a new package, even when the boss diameter looks unchanged.
What to Write for Each Threaded Feature
Location: balloon, boss name, or face ID
Four holes on the bottom is not a location if the part has two bottoms after a flip. Point to Feature A through Feature D or Balloons 20 to 23. Include cosmetic helices you do not want molded as threads, and mark those as appearance only so nobody cuts a release path for a style groove.
Route: molded, molded-in insert, or post-install
If an insert alternative is allowed on a molded thread, say so. Allowed means review may propose an insert if the internal release path is heavy. Not allowed means the molded thread must stay.
Class and engagement from the matching drawing revision
Write the class you will accept. Write engagement as a length or as modeled if the helix already shows it. Pull both from the drawing that matches this CAD revision. If the drawing is older than the solid, align revisions before you upload.
Resin-free crest, root, or start thread as keep-out
If flash on the thread will fail assembly, mark the thread resin-free. If a start thread can accept a witness, say witness allowed at the start. Reviewers gate and vent with that note.
Insert alternative allowed or forbidden on a molded thread
Another pattern: you have not chosen inserts yet but you know the holes are internal and small. Write internal, open to DFM on route, class as drawing, engagement as modeled, insert alternative allowed. That is still a specification. Internal TBD is not.
A worked per-thread block: Balloon 20, internal, post-install insert, brass, customer-supplied, drawing INS-M3-6, engagement as drawing, resin-free on the minor. Balloon 30, external, molded, class as drawing, engagement as modeled, insert alternative not allowed, keep-off on the crest.
RFQ Paste Block
Use this list once per threaded feature. Copy the pattern. Do not summarize four holes as threads in CAD.
- List every threaded feature by location.
- Pick molded, molded-in insert, or post-install.
- Add class and engagement.
- Attach insert drawings if hardware is used.
- Upload CAD through the injection molding instant quote platform.
A worked submit block: Rev E cover. Balloons 20-23 internal post-install inserts, customer-supplied, INS-M3-6, class and engagement as drawing. Balloon 30 external molded thread, class as drawing, insert alternative not allowed, crest keep-off. Appearance groove on Face 4, not a thread. That package can be reviewed.
What to tell sourcing: do not approve a quote that says threads as modeled. Ask for this checklist. If you already buy the inserts, say customer-supplied now so incoming is in scope. Hardware supply is your note. Each hole is a line item in the note, even when four holes share one insert.
Common mistakes at submit:
- Uploading a boss with a drilled hole and a thread only in the filename.
- Attaching three insert brands and asking the quote to pick.
- Changing class after the first click without changing the drawing revision.
- Writing tap in house as if that were a molding line.