Sweet box moulding output: boxes per hour by cycle and cavities at 97% good shots (calculated; cycles are illustrations, not machine claims)
| Cycle | 1 cavity | 2 cavities | 3 cavities |
|---|---|---|---|
| 6 s (600 shots/h) | 582 | 1,164 | 1,746 |
| 7 s (514 shots/h) | 499 | 998 | 1,497 |
| 8 s (450 shots/h) | 436 | 873 | 1,310 |
| 10 s (360 shots/h) | 349 | 698 | 1,048 |
Output is 3,600 divided by the cycle in seconds, times cavities, times the share of good shots. On a 260 t machine, a 250 g sweet box can run two or three cavities and a large food tray one, so for sweet box moulding on this press the two-cavity column is the one to read first. Cycle and cavities come from your mould trial, not from the table.
Key Takeaways
- Each term in the output formula is a separate lever: cycle, cavities and good-shot share, then effective hours a month.
- Wall thickness is squared in the cooling equation, so a wall 20% thinner needs about 36% less cooling time.
- Idling machines can draw 52% to 97.5% of full moulding energy, so idle hours belong in the cost plan.
- PP for food contact in India must conform to IS 10910, and packaging must meet an overall migration limit of 60 mg/kg.
How Many Sweet Boxes and Trays Fit on 260 t?
Two or three 250 g boxes, one or two 500 g boxes, one 1 kg box at conventional factors, and one large compartment tray where the wall is not thin. Sweet boxes with long flow and thin walls move toward the higher factor, which cuts the count.
Clamp per cavity for sweet boxes and trays, with a 10% reserve (calculated; sizes are assumptions)
| Item | Outline | Area | Factor 3 / 5 | Cavities at 260 t |
|---|---|---|---|---|
| 250 g sweet box | 150 × 100 mm | 150 cm² | 69.6 t / 116.0 t | 3 / 2 |
| 500 g sweet box | 190 × 130 mm | 247 cm² | 114.7 t / 191.0 t | 2 / 1 |
| 1 kg sweet box | 230 × 160 mm | 368 cm² | 170.8 t / 284.6 t | 1 / 0 |
| Compartment tray | 250 × 200 mm | 500 cm² | 232.1 t / 386.7 t | 1 / 0 |
The clamp method behind the table is in the container applications article, and the thin-wall factors are explained in the high-cavity thin-wall article in this series. A box with a 0.6 mm wall and long flow from a centre gate can pass 100:1, so test before you assume the lower factor.
The compartment tray shows how tight the limit gets. At a factor of 3, one tray needs about 232 t, which leaves 260 t with little to spare, and a thinner wall would push it past the machine. For trays, the wall you choose decides whether the job fits at all.
What Sets the Cycle Time for Sweet Box Moulding?
Cooling, which rises with the square of the wall. RJG's guidance on cooling time says wall thickness has the largest effect on it. In its trial on a 3.3 mm ABS part in an eight-cavity mould, about 85% of the cycle went to cooling.
Squaring cuts both ways. A box wall 20% thinner needs about 36% less cooling, because 0.8² is 0.64, but a thick corner or a heavy rim sets the pace for the whole part. RJG adds that only about 40% of the heat must be removed before ejection, and suggests adding about 20% to the calculated timer as a safety factor.
Trays are different from boxes. A compartment tray has ribs and dividers that meet the floor, and each junction is a thicker spot that cools last. Keep dividers thinner than the floor where the design allows, and core out heavy junctions.
How Do Lids, Colours and Idle Time Change the Plan?
They take hours away from the box mould. A lid has the box outline, so it needs similar clamp and often its own campaign. Every colour change and restart costs time and scrap, and a machine waiting between campaigns still draws power, so all three belong in the monthly plan.
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 about 1.5 hours may be cheaper to switch off and restart. Kent also notes that rising energy on the same job can point to screw or barrel wear.
If your demand rises before festivals, build box and lid stock ahead in long single-colour runs, and keep the short colour runs for quieter weeks. Good-shot share deserves the same attention: at two cavities and 7 s, slipping from 97% to 94% good shots loses about 31 boxes an hour, or about 17,650 a month over 22 hours and 26 days. Our view: plan on the cycle from your own trial, with lids and colour changes counted, because a plan built on the bare box cycle is always short.
Which Food-Contact Rules Apply to Sweet Boxes?
The FSSAI Packaging Regulations 2018. Plastics in direct food contact must conform to listed Indian Standards, IS 10910 for PP and IS 10142 for PS among them, and pass migration tests. The food business needs a certificate of conformity from an NABL-accredited lab for that packaging.
The overall migration limit is 60 mg/kg or 10 mg/dm², tested to IS 9845. There are specific migration limits for listed metals, such as barium at 1.0 mg/kg and zinc at 25.0 mg/kg. Pigments must meet IS 9833 and printing inks IS 15495, which matters for coloured and printed sweet boxes.
Recycled plastics may be used for food contact only as and when FSSAI frames standards and guidelines. Check this against the recycled-content targets in the container applications article before you plan any recycled share in a sweet box.
What Should You Send to Plan Sweet Box Output?
Send the box, lid and tray drawings with outline and wall thickness, the resin grade, monthly volumes, the number of colours, your peak months and the shifts you run. With these, cavities, cycle, effective hours and energy per thousand boxes can be planned before the mould is ordered. See the 260 ton horizontal injection moulding machine page.
Frequently Asked Questions About Sweet Box Moulding
Should sweet box lids snap or hinge?
Both work. A separate snap lid needs its own mould and campaign but stacks well and can be printed apart from the base. A hinged one-piece box saves a mould and assembly, but the hinge needs a grade and gate position that survive repeated flexing. Test hinge life before ordering production steel.
Why do sweet box walls show flow lines or gloss marks?
Flow lines often appear where melt fronts meet or where the fill hesitates at a thin section. Gloss marks can come from uneven mould temperature. Check fill speed, melt temperature and vent condition, then cooling balance across the cavity, before changing the grade or the gate.
How much does a colour change cost in output?
It depends on the colours and the purge method. Each change costs purge resin, start-up scrap and running hours. Moving from light to dark is easier than the reverse, so sequence colours light to dark and log the time and resin each change takes, then use those figures in the monthly plan.
Do printed sweet boxes need different packaging tests?
Printing inks used on food packaging must meet IS 15495 under the FSSAI Packaging Regulations 2018, and pigments must meet IS 9833. Ask your printer and masterbatch supplier for conformity documents, and include printed samples in the migration tests the NABL lab runs for the food business.
How should energy cost per thousand boxes be tracked?
Log kWh for each mould on a meter or clamp-meter logger, then divide by good boxes made. Use the rate from your latest electricity bill, since state tariffs can change, and include idle hours. A rising figure on the same mould can be an early sign of screw or barrel wear.
Related Articles
- What Can You Make on a 260 Ton Container Moulding Machine?
- Moulding Pails and Large Tubs on a 260 Ton Machine
- High-Cavity Thin-Wall Moulds on a 260 Ton Machine
Sources & References
- RJG Inc.: How to Determine Injection Molding Cooling Time
- PlasticsToday, R. Kent: Getting to know your real energy use and cost
- ExxonMobil, AMI and Tangram Technology: An Energy Saving Guide for Injection Moulders
- Food Safety and Standards Authority of India (FSSAI): Food Safety and Standards (Packaging) Regulations, 2018, compendium
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.
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