A one-cavity PP lunch box mould on a 120 t machine, at a 30 s cycle with 95% good shots, makes 3,600 ÷ 30 × 1 × 0.95 = 114 boxes an hour, or about 2,500 in a 22-hour day. Its lid needs the same machine time again. So one machine gives about 1,250 complete sets a day.
That number is the first figure to work out when starting a houseware unit. It tells you how many moulds one machine can keep busy, how much resin and power you will buy each month, and when a second machine starts to make sense. The cycle, cavities and hours are assumptions; put in your own.
Key Takeaways
- Output per hour is 3,600 ÷ cycle in seconds × cavities × good-shot share; a box and its lid share one machine's hours.
- Start with a product set in one resin whose moulds fit the clamp at the upper PP factor.
- Chillers, compressed air and water pumps together can take about a quarter of a moulding plant's energy.
- Plan energy at about 0.9 to 1.6 kWh per kg of variable load plus base load, priced at your latest bill's rates.
What Should a New Houseware Unit Make First?
Start with a product set whose moulds fit the clamp at the upper PP factor and run in one resin, such as a box and its lid. One resin avoids purging between jobs, and every mould change still adds to stock you can sell as a finished set.
The applications article in this series shows which parts fit 120 t and how to run the clamp check. The short version: single-cavity PP parts up to about 180 mm round fit, small items fit in multiples, and thin-wall tubs belong on a different kind of machine.
Check the rules before you cut steel. If your containers will be sold as rigid plastic packaging, the PWM (Amendment) Rules notified on 31 March 2026 set recycled content of at least 30% in 2025-26, rising to 60% by 2028-29, with exemptions where FSSAI and similar rules restrict recycled content. Penalties run from ₹10,000 to ₹15,00,000.
Some houseware resin datasheets also state the grade is not for single-use items banned under the PWM Rules, so confirm your product is not on that list. Our view: in the first year, run fewer moulds well rather than many moulds badly. A unit that knows three moulds inside out makes fewer rejects than one changing tools every shift.
What Equipment Does Starting a Houseware Unit Need Besides the Machine?
You need moulds for every part in the set, mould cooling through a chiller or cooling tower, compressed air, a granulator for runners and rejects, and weighing and packing space. The plant energy split shows why these auxiliaries deserve as much attention as the machine itself.
An energy guide from ExxonMobil, AMI and Tangram Technology gives a typical plant split: polymer processing 66%, chillers 11%, compressed air 10%, water pumps 5%, lighting 5%, heating 2% and offices 1%. It also estimates that about 30% of energy is discretionary in plants with no energy measures.
Small settings move those shares. The same guide says raising chilled water temperature by 1 °C cuts chiller cost by about 3%, that leaks typically waste 20% to 40% of compressed air, and that halving system pressure cuts its cost by three quarters. Set the chiller and the compressor to what the moulds need, not their maximum.
Monthly cost items for a one-machine houseware unit
| Item | What drives it | Where to check |
|---|---|---|
| Resin | Part plus runner weight, shots, reject rate, regrind use | Resin supplier quote and your shot weights |
| Machine energy | kWh per kg, base load, idle time | Clamp-meter readings on the actual job |
| Chiller and pumps | Water temperature setting, flow, hours | Chiller setpoint and meter readings |
| Compressed air | Pressure setting and leaks | Leak survey with the line pressurised and machines stopped |
| Moulds | One per part, including lids | Toolmaker quote and maintenance plan |
| Power bill terms | Tariff, demand charge, power factor | Your latest electricity bill |
What Will the Unit Cost to Run Each Month?
Resin and energy are the two large variable costs. Work out resin from shot weight and shots per month, then energy from kilograms processed. The same energy guide gives variable load of about 0.9 to 1.6 kWh per kg, with base load typically 20% to 40% of the total.
Idle time adds to that. A PlasticsToday article by Robin Kent reports idling machines drawing 52% to 97.5% of their full moulding energy, and suggests idle periods longer than 1.5 hours may be cheaper to switch off and restart. Plan breaks and mould changes with that in mind.
In Maharashtra, MERC issued an order on 25 March 2026 on MSEDCL's tariff petition after rulings by the Bombay High Court and the Supreme Court, and industrial tariffs from 1 July 2025 were affected. Use your latest bill for rates rather than an old tariff sheet. The 120 vs 125 ton article in this series covers kVAh billing.
Price the result against your selling price per set, not per kilogram. A lunch box set with a lid and clip uses three moulds' worth of machine time, so its margin depends on all three cycles. Track resin bought, sets packed and kWh used each month, and within a quarter you will have a cost per set built from your own figures instead of estimates.
What Should You Do Before Placing Orders?
Write down each product in the first set with part weight, runner weight, cavities, expected cycle and monthly demand. Work out machine hours per month, resin and energy, then check that one machine covers the hours with time for mould changes. See the 120 ton horizontal injection moulding machine page.
Frequently Asked Questions About Starting a Houseware Unit
Can I use recycled PP in houseware?
For items that do not touch food, recycled PP or your own regrind can work if colour and strength stay within limits, so trial it before committing. For food-contact items, check FSSAI rules first. If your product is sold as rigid packaging, the PWM Rules set rising recycled-content targets, with exemptions where food rules restrict recycled content.
Should I buy a chiller with the first machine?
If your moulds need water colder than a cooling tower can supply, yes. Cooling can take most of a thick-walled houseware cycle, so stable mould water pays back in output. Set the chilled water as warm as the moulds allow, since each 1 °C rise cuts chiller cost by about 3% according to the energy guide.
How do I measure what my machine actually uses?
Use a clamp-meter data logger on the machine supply. Robin Kent's PlasticsToday article says a machine can be measured in as little as 30 minutes, with heater load averaged over 10 to 15 minutes. Measure on a real job so you get kWh per kg for your own parts.
Is it cheaper to leave the machine idling during a break?
For short breaks, it can be, because heating up again takes time and energy. But idling machines can draw more than half their full moulding energy. Kent's article suggests that for idle periods longer than about 1.5 hours, switching off and restarting may cost less. Test it on your own machine.
How can I tell if the screw and barrel are wearing?
One sign is rising energy use on the same job with the same settings. Kent notes this can point to screw or barrel wear. Others are longer screw recovery, unstable cushion and more short shots. Logging kWh per kg each month gives you an early warning before quality slips.
Related Articles
- What Can You Make on a 120 Ton Household Moulding Machine?
- Moulding Mugs, Bowls and Lunch Boxes on a 120 Ton Machine
- 120 Ton vs 125 Ton Machine: Which Suits Houseware?
Sources & References
- ExxonMobil, AMI and Tangram Technology: An Energy Saving Guide for Injection Moulders
- PlasticsToday, R. Kent: Getting to know your real energy use and cost
- Polymerupdate, D. K. Jha: India eases plastic recycling regulations
- Deccan Chamber of Commerce, Industries and Agriculture, Pune: Circular No. 085: MERC Order dated 25th March 2026
Technical Disclaimer
Disclaimer: The information provided in this document is for general informational and educational purposes only. It is based on technical references and industry information available at the time of preparation and may be subject to change. It does not constitute engineering, technical, commercial or professional advice, nor does it constitute a quotation, specification, warranty or contractual commitment by Pratishna Engineers.
Actual injection moulding machine and process requirements vary according to the component design, material, mould, production volume, machine configuration and operating conditions. The information, examples, calculations and recommendations provided should be independently evaluated and verified for the specific application before making any equipment, process or production decision. Information obtained from third-party sources remains subject to the accuracy and limitations of those sources.
Limitation of Liability: Pratishna Engineers makes no representation or warranty, express or implied, regarding the completeness, accuracy or suitability of the information for any particular application. To the extent permitted by applicable law, Pratishna Engineers shall not be liable for any loss, damage, cost or consequence arising from reliance on or use of the information contained in this document. Final machine selection, configuration and application suitability should be confirmed with Pratishna Engineers based on complete and accurate project requirements.
