Introduction
In 2000, G-Fast Distribution received an order for 1,500 custom adjustment screws used in a new optical laser sight system. The customer, a venture-backed technology company serving sporting, military, and law-enforcement markets, required a robust field-adjustable fastener that could be tightened by hand or with a coin. The part featured a large knurled head, precision shoulder, reduced shank diameter and 6-32 threaded end.
The Original Design
The adjustment screw incorporated a 0.630-inch diameter knurled head with a coin slot, a 0.230-inch by 0.400-inch shoulder, a reduced 0.138-inch diameter shank, and 0.44 inches of 6-32 UNF threads. Through discussions with the customer’s engineering team, 4140 alloy steel was selected and heat treated to performance levels comparable to ASTM A574 socket head cap screws.
Prototype Production
The initial order was produced on Swiss screw machines. Swiss machining was ideal for prototype quantities because it allowed all required diameters, shoulders, and features to be manufactured complete prior to heat treatment and plating. Testing validated both the product design and field performance.
The Manufacturing Challenge
As market demand increased, projected quantities expanded into the 10,000–25,000 piece range. Continuing to manufacture the component entirely by Swiss machining would have resulted in unnecessarily high production costs. G-Fast initiated a Fasteneering® review to determine whether the design could be adapted to a more economical manufacturing method.
The Fasteneering® Solution
Working with the customer, G-Fast evaluated material selection, manufacturing processes, tolerances, and secondary operations. The part was redesigned for cold-heading using cold-heading quality alloy steel wire. Certain machining tolerances were adjusted to levels compatible with high-volume production while preserving functional performance.
Manufacturing Sequence
The accompanying photograph illustrates the production sequence in a clock pattern beginning at approximately the 7:30 position:
1. Cold-headed blank
2. Knurling operation
3. Slotting operation
4. Diameter grinding for thread preparation
5. Thread rolling
6. Heat treatment
7. Scale removal and surface preparation
8. Final plating
9. Finished adjustment screw
Quality and Traceability
Each manufacturing operation was controlled through documented work instructions and lot traceability. Heat treatment certifications, plating certifications, inspection records, and lot identification were maintained throughout production. Finished parts were inspected by G-Fast and packaged with lot identification and date-of-manufacture information.
Results
The conversion from Swiss machining to cold-heading reduced the customer’s piece-part cost by more than 75 percent. The redesign also provided significantly greater manufacturing capacity and long-term supply stability. Monthly demand eventually increased to between 5,000 and 8,500 pieces. Between 2001 and 2011, more than 875,000 pieces of this adjustment screw were produced.
Fasteneering® Takeaway
This project demonstrates how manufacturing expertise can create substantial value without changing the function of a part. By reviewing the design, selecting the appropriate manufacturing process, and implementing a scalable production strategy, G-Fast helped transform a successful prototype into a high-volume production component. The greatest savings often come not from changing suppliers, but from improving the way a part is manufactured.