Choosing between time and materials (T&M) and fixed-price contracts in injection molding can make or break your profitability and client relationships. The wrong model leaves you either eating costs on complex projects or turning away work because you can't price it accurately. Here's how to evaluate both approaches and match them to your operation.
Understanding Time and Materials Pricing
Time and materials contracts charge clients for actual labor hours, machine runtime, and material consumed—plus a markup. You bill $75–$150 per hour for skilled molding technicians, material costs at cost-plus 15–25%, and machine time at $200–$500 per hour depending on machine size and complexity.
This model protects you against scope creep and unforeseen tooling adjustments. If a client's design requires unexpected gate modifications or cooling channel revisions, you absorb nothing—you simply invoice the extra work. For shops with older equipment or less predictable jobs, T&M reduces your financial exposure.
The downside: clients see invoices ballooning and lose confidence in cost control. Many purchasing managers reject T&M entirely because they can't budget accurately.
Fixed-Price Contracts: Control and Risk
Fixed pricing locks in a total cost for mold design, fabrication, and first production run. A simple single-cavity mold for a small consumer product might run $8,000–$15,000; a complex multi-cavity tooling project with advanced cooling could hit $40,000–$80,000.
You control margin by front-loading estimation. You analyze the CAD file, define cavity count, material flow, cooling requirements, and post-mold finishing—then bid accordingly. When execution matches your plan, fixed pricing delivers strong profit.
The catch: underestimating design complexity or material behavior eats directly into profit. A client who requests mid-project design changes can claim scope creep, creating conflict.
When to Use Each Model
Use time and materials for:
- Prototype molds (1–5 cavities, experimental materials, uncertain cycle times)
- Projects with undefined specifications or client-driven iterations
- Repair, maintenance, or reverse-engineering work
- Clients with proven track records who accept variable invoices
Use fixed price for:
- Production tooling with locked specifications
- Clients requesting formal quotes for purchasing or capital approval
- Jobs where you've built similar molds before (reducing estimation risk)
- Competitively bid projects where T&M won't win the work
Hybrid Approaches That Work
Many molders split the difference. You charge a fixed price for mold fabrication (where you have cost control) and T&M for secondary operations like ultrasonic welding, pad printing, or custom packaging—since those vary per production volume.
Another hybrid: fixed mold cost + T&M for the first 10,000 parts, then move to per-piece pricing after proving design and process stability. This aligns incentives—you're motivated to get the mold right quickly, and clients see transparent cost scaling as volume climbs.
Calculating Your Numbers
Pull your actual data. Track 5–10 recent projects: total labor hours, machine hours, material waste, and actual profit margin. If you're consistently underestimating mold complexity by 15–20%, your fixed quotes are too aggressive.
For T&M jobs, document the hourly labor breakdown (design, CNC setup, manual finishing, quality inspection) and machine runtime. Most molders find that overhead allocation adds 30–50% to direct labor cost—account for it in your markup.
Building Client Confidence in Either Model
Transparent scope definition wins either way. Provide a detailed quote that lists mold cavities, cooling strategy, anticipated cycle time, material shrinkage compensation, and post-mold finishing. If you outline T&M work by phase (design, rough tooling, finish, first trials, adjustments), clients see they're paying for real work, not guessing.
Listing your services on Mercoly helps you reach clients actively seeking molders and lets you set clear terms upfront—whether fixed or T&M—so expectations align before work starts.
Frequently Asked Questions
Q: Should I always require a non-refundable deposit for fixed-price molds? Yes—typically 30–50% down to secure material, design engineering time, and CNC programming. The balance comes due before delivery or at first article inspection, depending on your contract.
Q: What percentage of mold cost is usually labor vs. material? For a standard production mold, expect roughly 50–60% labor and engineering, 20–25% material (steel, inserts, lubricants), and 15–25% overhead and profit allocation.
Q: How do I protect myself if a fixed-price client keeps requesting design changes? Lock the scope in writing before quoting—specify cavity count, material grade, surface finish, and dimensional tolerance range. Any change outside that scope is a separate change order billed T&M.
Ready to grow your molding business? Start winning customers on Mercoly today.