Recreation
Overmolding & Sonic Welding
Industry: Sports/Recreation
Product: Fillet Knife Handle
Services: Engineering, Manufacturing, Assembly & Decoration
The Challenge
A customer in the recreational products industry needed a fillet knife handle that combined attractive aesthetics, strong ergonomics and reliable performance — all at an economical price point. The 5” long, 0.75” thick handle required a rigid structural core with a soft, tactile overmolded exterior, and the design needed to capture the knife blade securely through mechanical interlocks.
The Approach
R&D Plastics collaborated with the customer through design, development and material selection to ensure the part could be manufactured economically and consistently. The team selected a glass-reinforced polypropylene core substrate with a Santoprene overmolded exterior. After molding, the substrate halves are sonically welded together, then overmolded — producing a complete handle ready for blade assembly. The design combines mechanical locking with elastomer fusion for strong material retention.
The Result
The handle is molded to tolerances of ±0.010” and tested for proper adhesion of the overmold to the substrate and weld quality. The finished product is a simple-to-assemble, highly functional handle with excellent ergonomics and tactile feel — delivered in a typical production lead time of five weeks.
Highlights
| Specifications | Details |
|---|---|
| Product Description | These knife handles are for recreational outdoor use. |
| Capabilities Applied / Processes | Primary: Engineering (Product Development/Design, Material Selection), Injection Molding, Sonic Welding, Over-molding |
| Equipment Used to Manufacture Part | 110-Ton All-Electric Toshiba |
| Overall Part Dimensions | 5” long x 0.75” thick |
| Tightest Tolerances | ±0.010” |
| Material Used | Glass-Reinforced Polypropylene/Santoprene |
| Mold Finish | Heavy Chemical Etch-Textured |
| In-Process Testing / Inspection | Testing for adhesion of the over-mold to the substrate, as well as functional fit check of the ultrasonically welded substrates |
| Industry for Use | Sports/Recreation |
| Delivery / Turnaround Time | Five (5) weeks typical production lead time |
| Delivery Location | FOB our facility |
| Standards Met | Customer Specifications |
| Product Name | Fillet Knife Handle |
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