Class Code 3339
Foundries – Investment Casting
Class Code 3339 covers investment casting (lost‑wax) foundry operations, a high‑heat, precision process used to produce complex metal parts. The September 1, 2026 approved pure premium rate for this class is $5.926 per $100 of payroll — an important baseline for budgeting workers' compensation costs.
What Class Code 3339 Covers
This classification applies to foundries using the investment (lost‑wax) casting process: wax pattern production, assembly of gating and sprues, ceramic shell building (dipping/stuccoing), burnout/dewaxing ovens, metal melting (induction, crucible or gas-fired furnaces) and pouring into ceramic shells, shell knockout and finishing (shot blasting, grinding, machining), and related inspection/heat‑treat operations. It covers on‑site pattern makers who produce wax patterns, technicians operating shell lines and burnout ovens, furnace and pour crews, and finishing staff who remove ceramic shells and perform machining or surface treatment. Processes that are strictly sand casting, die casting, or foundry work outside investment casting are typically classified differently. Payroll for clerical or administrative staff at the foundry location should be handled according to clerical classification rules and separated from this operational payroll.
Who It Applies To
- Investment casting foundry owners and operators (lost‑wax process)
- Wax pattern makers and assemblers
- Shell building, dipping, stuccoing and drying technicians
- Furnace operators and pour crews (induction, crucible or gas furnaces)
- Shell knockout, blasting and finishing personnel (grinders, machinists)
- Quality control, metallurgical testing, and heat‑treat technicians on the production floor
Common Job Duties
- Creating and assembling wax patterns and gating systems
- Applying ceramic slurry and stucco layers to form shells, and drying them
- Burnout/dewaxing of shells using ovens, autoclaves or steam systems
- Melting metal and pouring molten metal into ceramic shells
- Knocking out shells, blasting/derusting castings, and grinding/finishing
- Operating and maintaining induction/crucible furnaces and ladles
- Inspecting castings, performing heat treatment and dimensional checks
Common Injury Risks
Understanding the $5.926 Rate
The approved pure premium rate of $5.926 per $100 of payroll is the base cost to insure the injury risk for this class — multiply your payroll for these operations (in hundreds) by 5.926 to get the pure premium. The final premium an employer pays will be adjusted by the insurer's expense constants, the employer's experience modification (loss history), any schedule or retrospective rating plans, policy-level deductibles, and correct payroll classification splits between job types.
Cal/OSHA Compliance Requirements
Investment casting foundries must comply with Cal/OSHA standards for respirable crystalline silica control, including exposure assessment, engineering controls (local exhaust and dust collection), medical surveillance and written exposure control plans where applicable. Other key requirements include an effective respiratory protection program, hazard communication for binders and release agents, hot‑work and lockout/tagout procedures, heat illness prevention for employees working near furnaces, and hearing conservation when noise exposures exceed limits.
How Key HR Helps Employers Under Class Code 3339
A PEO like Key HR helps investment casting employers by providing workers' comp program administration, claims management and return‑to‑work coordination to limit costly indemnity claims. Key HR can also deliver compliance support — written silica control and respirator programs, training for furnace and pour crews, safety audits, and centralized procurement of PPE — all of which help reduce losses and lower experience modification factors over time.
Get a QuoteFrequently Asked Questions
Does class code 3339 cover pattern making and wax work done at the foundry?
Yes. Wax pattern fabrication and assembly performed as part of on‑site investment casting operations are included in Class Code 3339. If pattern work is outsourced to a separate business with different processes, that payroll may be classified separately.
What specific Cal/OSHA programs are typically required for investment casting operations?
Foundries should expect to implement a respirator program, a written silica exposure control plan where shell materials or grinding generate silica dust, hazard communication for binders and solvents, hot work permits and fire prevention, lockout/tagout for equipment servicing, heat illness prevention for furnace areas, and hearing conservation as needed.
How can I lower my workers' compensation costs for investment casting work?
Focus on engineering controls (local exhaust, enclosed shell lines, automated pour systems), effective dust collection and housekeeping, documented respiratory and PPE programs, targeted training for pour and finishing crews, proactive light‑duty return‑to‑work, and routine safety audits — all reduce injuries and improve your experience modification, which lowers premiums.
Quick Facts
- Class Code
- 3339
- Classification
- Foundries – Investment Casting
- Pure Premium Rate
- $5.926 / $100 payroll
- Effective Date
- September 1, 2026
- Source
- WCIRB Approved Filing
Manage Workers' Comp Through a PEO
Key HR provides pay-as-you-go workers' comp for California employers — no large deposits, no audits, better rates.
Get a Quoteor call (800) 922-4133Ready to Simplify Workers' Comp for Class Code 3339?
Key HR provides California employers with pay-as-you-go workers' comp, HR compliance support, and payroll — all through one PEO partnership.