Cap Compression Moulding Machine-Zhangjiagang Grandee Machinery Co., Ltd.

Both compression moulding and injection moulding are widely used for high-volume cap production, but they differ significantly in principle, equipment, cycle time, product quality, and cost structure. Below is a side-by-side technical comparison to help you determine which process best suits your production goals.
1. Equipment & Mould Structure
Aspect Compression Moulding Injection Moulding
Machine Structure Rotary carousel with simple vertical clamping Complex horizontal injection unit + clamping system
Mould Design No runner, no gate – simple structure Requires hot runner and gate system – complex
Clamping Force Lower (10–30 MPa) Higher (70–150 MPa)
Mould Cost Lower Higher
2. Cycle Time & Productivity
Aspect Compression Moulding Injection Moulding
Cycle Time Faster: 3–6 seconds Slower: 5–10 seconds
Typical Cavitation Lower: 32–64 cavities Higher: 64–144+ cavities
Energy Consumption Lower (lower temperature + continuous rotary operation) Higher
Output per Hour Very high for dedicated single-design lines High, with more flexibility
3. Cost & Investment
Injection Moulding Machine: Initial Investment Lower (simpler machine + mould) Higher (complex machine + hot runner)
Cap compression machine: Per-Part Cost (High Volume) Lower Slightly higher
Material Waste Minimal – no runner waste Small – hot runner minimizes waste, but some material remains in system
Maintenance Simpler – fewer moving parts More complex – requires skilled technicians
4. When to Choose Which?
Scenario Recommended Process
Annual volume < 50 million caps Injection Moulding – more flexible
Annual volume 50–200 million caps Either – depends on other factors
Annual volume > 200 million caps Compression Moulding – dedicated high-speed line
5. To help you decide:
· Choose Compression Moulding if you produce high volumes (>200 million/year) of a single, simple cap design (e.g., standard flat-top water caps) and prioritise low per-part cost, fast cycle time, and superior appearance (no gate mark).
· Choose Injection Moulding if you need design flexibility (tethered caps, sport caps, linerless designs), moulded-in tamper bands (no post-processing), micro-plastic-free production, or if you run mixed SKUs with frequent changeovers.
Could you share your target annual output, cap design complexity, and whether you plan to run multiple cap types on the same line? I can then provide a more tailored recommendation with cost estimates.

Absolutely. Our compression molding platform is tooled to produce a wide range of neck finishes, including the 28mm, 30mm, and 38mm sizes you mentioned. Cap Types Available: We specialize in smooth-walled CT caps, TE (tamper-evident) bands, and child-resistant (CRC) closures, with options for both standard and deep-skirt designs. Material & Process: We primarily run with virgin HDPE and PP resins. Our multi-cavity molds (up to 32/48 cavities) ensure high output with tight dimensional tolerances (typically ±0.05mm) and a flash-free finish, thanks to the compression process. If you have a specific liner requirement (EVA, PE, or induction foil) or need a particular height/drop-down, we can adjust accordingly.

Our output speed is highly dependent on the cavity count and the cap design/weight. For a standard 28mm / 30mm lightweight water cap (approx. 2.2–2.8g), our 32-cavity compression press runs at a cycle time of 28–32 cycles/minute, yielding approximately 53,000 to 61,000 caps per hour (theoretical UPH). For a larger 38mm cap (heavier weight), the cooling phase extends the cycle time to about 22–25 cycles/minute, which translates to roughly 42,000–48,000 caps per hour on the same 32-cavity tooling. We can also offer 48-cavity or 72-cavity systems for higher output if required.

1. Vacuum hopper loader for automatic material feeding. 2. Gravimetric batch mixer or masterbatch dosing unit for accurate colorant and regrind blending (ratio control within ±0.5%). 3. Central water chiller with flow meters and solenoid valves for each mould station. This is the most critical auxiliary—compression moulding requires extremely stable cooling water temperature (±1°C) to control cap weight, shrinkage, and inner diameter consistency. 4. Cap unscrambler / orienter (if directly feeding to a capping machine) or stacking/counting unit for bulk packaging. 5. Cap cooler machine 6. Quality Assurance System (Highly Recommended) In-line CCD vision inspection system for real-time detection of flash, shorts, outer diameter, and height deviations. Optional torque/leakage tester for random sampling.