Mould material comparison
The choice of mould material is the most important tooling decision in thermoforming. It determines cycle time, surface finish, dimensional accuracy, and total cost of ownership:
| Material | Tooling Cost | Cycle Life | Surface Finish | Heat Transfer | Best For |
|---|---|---|---|---|---|
| Machined Aluminium | ₹1–25L | 500,000+ cycles | Excellent (Ra 0.4μm) | Excellent | Production runs, tight tolerances |
| Cast Aluminium | ₹50K–5L | 100,000+ cycles | Good (Ra 1.6μm) | Good | Medium volume, complex shapes |
| Epoxy Resin | ₹15K–1L | 500–5,000 cycles | Good (Ra 1.6μm) | Poor | Prototypes, low volume < 500 parts |
| Wood (MDF/Hardwood) | ₹5K–30K | 10–200 cycles | Fair (Ra 3.2μm) | Very poor | Concept prototypes only |
| 3D Printed (SLA/SLS) | ₹5K–50K | 5–50 cycles | Fair–Good | Very poor | Concept validation, single parts |
| Steel | ₹5L–50L+ | 1,000,000+ cycles | Excellent | Good | Very high volume, abrasive materials |
Male vs female mould: which surface gets the best finish?
The surface that contacts the mould gets the best finish and tightest dimensional control. The free surface (not in contact with the mould) is determined by the material's natural shrinkage and sag:
Female (cavity) mould
- •Inside surface contacts mould → best finish on inside
- •Better dimensional control on inside dimensions
- •More uniform base thickness
- •Less draft required (1–3°)
- •Best for: trays, packaging, enclosures, covers
Male (core) mould
- •Outside surface contacts mould → best finish on outside
- •Better dimensional control on outside dimensions
- •More draft required (3–7°)
- •Thinner base (material stretches over core)
- •Best for: automotive liners, bath products, deep containers
Mould temperature control
Mould temperature has a direct impact on cycle time and part quality. Aluminium moulds can be water-cooled (channels drilled through the mould body), reducing cycle time by 30–50% compared to air-cooled moulds.
| Cooling Method | Mould Temp Range | Cycle Time Impact | Tooling Cost Premium | Best For |
|---|---|---|---|---|
| Air cooling (ambient) | 30–60°C | Baseline | None | Low volume, prototypes |
| Water cooling (internal channels) | 15–40°C | −30 to −50% | +20–40% | Production runs, thick sheets |
| Heated mould | 60–120°C | +10–20% | +30–50% | Crystalline materials (PP, HDPE), textured surfaces |
Mould selection decision guide
1–10 parts (concept validation)
→ 3D printed SLA or wood mould (₹5K–30K)
Fastest and cheapest. Surface finish is fair. Not suitable for production.
10–500 parts (prototype / pilot)
→ Epoxy resin mould (₹15K–1L)
Good surface finish. Adequate for pilot runs. Replace with aluminium for production.
500–10,000 parts (low volume production)
→ Cast aluminium mould (₹50K–5L)
Good finish, adequate life. Water cooling optional.
10,000–500,000 parts (medium volume)
→ Machined aluminium mould with water cooling (₹1L–15L)
Excellent finish and dimensional accuracy. Water cooling essential for cycle time.
500,000+ parts (high volume)
→ Machined aluminium or steel, multi-cavity (₹5L–50L+)
Multi-cavity moulds reduce per-part cost. Steel for abrasive materials.
Frequently asked questions
What material is used for thermoforming moulds?
Thermoforming moulds are made from aluminium (most common for production), epoxy resin (prototyping and low volume), wood (very low volume prototypes), and 3D printed materials (concept prototypes). Aluminium is preferred for production because it conducts heat efficiently, allowing faster cycle times, and can withstand millions of cycles. Epoxy moulds are 5–10× cheaper than aluminium but last only 500–5000 cycles.
How much does a thermoforming mould cost?
Thermoforming mould costs range from ₹15,000–₹50,000 for a simple epoxy or wood prototype mould, ₹1–5 lakh for a machined aluminium mould for a medium-complexity part, and ₹5–25 lakh for a complex multi-cavity aluminium mould with temperature control. Compared to injection moulding, thermoforming moulds are typically 5–20× cheaper, making them ideal for low-to-medium volume production.
When should I use a male mould vs a female mould for thermoforming?
Use a female (cavity) mould when the inside surface of the part needs the best surface finish and dimensional accuracy — the sheet contacts the mould on the inside. Use a male (core) mould when the outside surface needs the best finish — the sheet contacts the mould on the outside. Female moulds give better detail on the inside; male moulds give better detail on the outside. Female moulds also give more consistent wall thickness at the base.