The 350 ton two platen vs toggle choice turns on how the clamp opens, not how hard it locks. Both give 350 t. The table sets out how the designs differ, as reported in two trade sources.
How toggle and two-platen clamps differ, as reported by M. Knights (Plastics Technology) and B. Catoen (MoldMaking Technology); builder claims are marked
| Point | Toggle clamp | Two-platen clamp |
|---|---|---|
| How it locks | A linkage straightens and locks the moving platen | Split nuts or similar lock the platen on the tie bars; short-stroke cylinders build tonnage |
| Opening | Full stroke at every mould height | Maximum daylight is minimum mould height plus stroke, so opening falls as mould height rises |
| Machine length | Longer | Shorter than a toggle or fully hydraulic machine |
| Force on the platen | Applied near the corners; potential for higher platen deflection | Builders claim more uniform pressure and finer control |
| Speed and opening force | Builders claim slightly faster lock-up and greater opening force | Builders claim a greater mould-height range |
Choose the two-platen machine when the part is tall, the mould is tall or floor length is short. For shallow household parts that fit a toggle's stroke, the toggle remains a sound choice.
Key Takeaways
- A toggle gives its full stroke at any mould height; a two-platen machine gives daylight minus mould height.
- A two-platen machine opens wider than a toggle whenever mould height is below its daylight minus the toggle's stroke.
- Under the assumptions in this article, the tallest part rises from about 240 mm on the toggle to about 354 mm on the two-platen machine.
- A machine far larger than the job carries a high base load, and Maharashtra's kVAh billing makes power factor count too.
350 Ton Two Platen vs Toggle: Which Parts Decide?
Tall parts and tall moulds. Dustbins, deep crates, stools and large tubs need an opening of about 2.5 times their height, and their moulds are tall as well. Where a toggle's fixed stroke cannot clear the part, the two-platen machine's longer opening decides the choice.
Bruce Catoen's MoldMaking Technology guide gives both relationships. On a toggle, maximum daylight equals maximum shut height plus stroke, and the full stroke is available at every shut height. On a piston-type clamp, which his figure shows as a two-platen machine, maximum daylight equals minimum shut height plus maximum stroke.
So the two clamps cross over. The two-platen machine opens wider whenever the mould height is less than its maximum daylight minus the toggle's stroke. Above that height, the toggle opens wider, if the mould still fits its maximum shut height.
Take-out also uses opening. A robot arm or a gripper for a deep part needs room beside the core as well as above it, so the 2.5 times rule is a starting check. Agree the take-out method with the mould maker and robot supplier before fixing the machine.
How Do the Openings Compare at Each Mould Height?
With assumed figures, the gap is large. Take a toggle with 600 mm stroke and 650 mm maximum mould height, and a two-platen machine with 1,200 mm stroke and 300 mm minimum mould height, giving 1,500 mm daylight. The two-platen machine opens wider up to a 900 mm mould.
Usable opening by mould height (assumed machines: toggle 600 mm stroke, 650 mm maximum mould height; two-platen 1,200 mm stroke, 300 mm minimum mould height, 1,500 mm daylight)
| Mould height | Toggle opening | Two-platen opening |
|---|---|---|
| 350 mm | 600 mm | 1,150 mm |
| 450 mm | 600 mm | 1,050 mm |
| 550 mm | 600 mm | 950 mm |
| 650 mm | 600 mm | 850 mm |
| 750 mm | Does not fit | 750 mm |
Real machines differ widely in stroke and mould height range, so compare the data sheets on these lines before tonnage. Catoen also asks you to confirm that the mould fits within the tie bars and that its weight suits both platens.
What Else Changes Besides the Opening?
Length, maintenance and how the force reaches the mould. Mikell Knights' Plastics Technology article reports that two-platen hydromechanical machines are shorter overall than toggles, which can matter in an existing bay where a 350 t toggle would block an aisle.
Knights lists drawbacks cited for toggles: a narrower stroke-adjustment range, possible over-clamping if mould height is set cold and the mould then expands, parallelism risk as linkages wear unevenly and grease contamination. Toggle defenders, he notes, point to reliability, simplicity and rigidity.
Mould changes differ too. Knights reports that some builders say toggles take longer to set up for a new mould, because mould height has to be adjusted through the linkage. A plant that changes large moulds every week should time a mould change on each machine type during trials.
Some builders quoted in the article claim toggles lock up slightly faster and give greater opening force, which can help deep-draw parts. These are reported claims, not measured results, so ask for dry-cycle and opening-force figures for the actual machines you compare.
Does the Bigger Machine Cost More to Run?
It can, if it is too large for the job. The ExxonMobil, AMI and Tangram energy guide says a standard hydraulic machine's base load can be 75% or more of its energy, and that a high base load can mean the machine is too large.
The same guide puts all-electric and hybrid base loads at about 10 to 20%, mostly barrel heating, and says ten-year energy cost exceeds purchase cost in almost every case. So compare the drive and pump type of each machine, not only its clamp design, before comparing prices.
In Maharashtra, MSEDCL's kVAh billing puts demand charges on kVA and energy charges on kVAh, and MERC intended it for all HT consumers and LT consumers above 20 kW from April 2020. Poor power factor then raises the bill directly. The FAQ notes that at a power factor of 0.85, 15% of the power does no useful work, and recommends capacitors or APFC panels.
Our view: choose the two-platen machine for depth, mould height or floor length, not for tonnage. If the parts you will run for the next few years are shallow and fit a toggle's stroke, the extra opening is capacity you pay for and never use.
What Should You Send for a Clamp-Type Comparison?
Send the tallest part's height and outline, the mould maker's estimate of closed mould height and weight, and the floor space available. Opening, mould fit, tie-bar gap and length can then be compared for both clamp types. See the 350 ton two platen injection moulding machine page.
Frequently Asked Questions About Two-Platen and Toggle Machines
Is a two-platen machine always better for large parts?
No. It suits tall parts and tall moulds, and saves length. A wide but shallow part, such as a tray or lid, gains little from the extra opening, and a toggle of the same tonnage may cycle as fast or faster. Decide by the tallest part and mould you will run.
Why does opening fall as mould height rises on a two-platen machine?
Because its maximum daylight is fixed by the minimum mould height plus the full stroke. A thicker mould takes up part of that daylight, so less is left for opening. A toggle's linkage instead keeps the full stroke available at every mould height within its range.
Does a two-platen machine need a stronger foundation?
Any 350 t machine needs a level, solid floor rated for its weight and the mould's. A shorter machine concentrates its weight on a smaller footprint. Ask the machine supplier for foundation loads and levelling requirements, and have a structural engineer check older floors before installation.
Can a toggle machine run a heavy mould?
Within its rated mould weight, yes. Heavy moulds on a toggle can add wear to the moving platen guides and linkage if they exceed the rating. Check the maximum mould weight for both platens on each machine's data sheet, since tall, deep moulds are often the heaviest.
Which clamp gives more even pressure on flat parts?
Builders quoted in trade articles claim direct hydraulic clamping gives more uniform pressure, while toggles apply force near the platen corners. These claims are not test results. Mould size relative to the tie-bar gap, support pillars and platen parallelism matter as much as the clamp type.
Related Articles
- What Can You Make on a 350 Ton Two Platen Machine?
- Large Crates and Tables on a 350 Ton Two Platen Machine
- Shot Weights Up to 1.5 kg: Screw Choice on a 350 Ton Machine
Sources & References
- MoldMaking Technology, B. Catoen: Machine Sizing and Specification for Optimal Mold Performance, Part 1
- Plastics Technology, M. Knights: Hybrid Injection Clamps: The Best of Both Worlds?
- ExxonMobil, AMI and Tangram Technology: An Energy Saving Guide for Injection Moulders
- Maharashtra State Electricity Distribution Co. (MSEDCL): kVAh Billing: Frequently Asked Questions
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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