The shear jaw body is the load-bearing jaw that carries the cutting blade and the anvil on a cast-removal shear used to split plaster and fibreglass casts. OEMs replacing a machined-from-solid jaw see cost pressure at low-to-mid volumes, while field failures appear as cracked pivot bosses and worn anvil lands. Ningbo Ruican casts the jaw profile net shape in precipitation-hardening stainless and machines only the pivot bore, blade seats and anvil land, holding ±0.02 mm concentricity between pivot and blade seat.
Specifications
| Casting process | Material options | Dimensional tolerance (ISO 8062-3 CT grade) | Machining | Surface finish (Ra) | Weight range | Typical lead time |
|---|---|---|---|---|---|---|
| Silica sol lost-wax investment casting, H900 or H1025 heat treatment to print | 17-4PH (H900 / H1025), AISI 420 | CT5–CT6 as cast; CT4 on pivot bore, blade seat and anvil land | CNC milling, boring, reaming and wire-EDM slotting of the blade pocket | Ra 0.8 um machined; Ra 0.4 um on anvil land after fine grinding | 45–180 g | 30–45 days including First Article Inspection report |
Scope and options
Key features
- Moreover, Pivot boss reinforcement ribs are cast in, removing the stress risers typical of pocket-milled solid jaws.
- Heat treatment to H1025 gives the fracture toughness needed for repeated prying loads on fibreglass casts.
- Generally, Pivot bore and blade pocket share one fixturing datum, holding concentricity inside 0.02 mm.
- Magnetic particle inspection per ASTM E709 available on the pivot section at 100 percent coverage.
- Additionally, Near-net casting reduces buy-to-fly ratio by roughly half compared with 17-4PH bar stock.
- Serialised traceability supports OEM spare-parts distribution and field-recall traceability if ever required.
Applications
- Manual orthopaedic cast-removal shears for plaster of Paris
- Heavy-duty shear jaw bodies for fibreglass and synthetic casting tape
- Powered oscillating cast saw shear attachments and cast splitters
- Paediatric cast-removal shears with reduced jaw profile
- Veterinary cast and splint removal shears
- Emergency department trauma shears with replaceable hardened jaw bodies
Quality & compliance
Ningbo Ruican is not an ISO 13485 contract manufacturer. It supplies cast and CNC-machined components in 17-4PH (H900/H1025), AISI 420 and AISI 316L together with project-level documentation under the customer’s Quality Agreement, including material traceability and ISO 10993-5 biocompatibility test support. Hardness mapping across the pivot boss, PMI reporting where specified, and heat-treatment charts tied to load number are delivered with each lot, so the OEM service-parts chain stays auditable.
Which hardness condition do you recommend for this jaw?
We recommend H1025 for most cast-removal shear jaws. The higher temper gives better impact toughness and resistance to cracking at the pivot boss during prying loads on fibreglass casts, while still holding roughly 35 HRC. Where the print specifies H900 for maximum edge stability, we will flag that the tougher alternative exists and let the engineering team decide.
Can you match an existing OEM jaw for service parts?
Yes. Most service-part programs start from a sample plus a reverse-engineering report. We scan the part, build a drawing for your approval, then confirm material equivalence in 17-4PH or AISI 420 before tooling. We cannot reproduce a name-brand marking, but we can cast your own part number or logo into the jaw body under written authorisation.
How is the pivot bore accuracy held after heat treatment?
We rough-machine the pivot bore, then perform solution annealing and ageing, and finish-bore afterwards so heat-treatment distortion cannot enter the tolerance chain. Each part is verified on a CMM or with air gauging, and the concentricity result between pivot bore and blade seat is recorded on the inspection report for every serialised unit.
Do you test prototype jaws destructively?
Moreover, we can run a limited destructive validation at quotation stage. Typical work includes torque-to-failure on the pivot, cyclic shear testing on synthetic casting tape to ten thousand cycles, and sectioning to check for shrinkage porosity in the boss. Results are reported to you as raw data, not as a certified verification, since we are not the device manufacturer.
What is the minimum viable order quantity?
Tooling economics and shell runs usually place the practical starting point around three hundred pieces per heat-treat lot, though we have supported pilot batches of fifty for reverse-engineering programs on a tooling-plus-piece-price basis. Water glass casting can improve piece price above about five thousand annual pieces if the tolerance class allows it.
CTA
Send your shear jaw drawing, hardness requirement and expected break-even annual usage and we will return casting plus machining pricing with a tooling amortisation schedule. Contact Wendy She — sales@cnsandcasting.com — WhatsApp +86-13777124360 to arrange a sample evaluation service part build.
