PET Preform Machine Buying Checklist: 12 Specs to Confirm Before You Compare Quotes

Why two quotes are almost never comparable

Two suppliers quote "270 ton PET preform machine" at very different prices. On paper they look like the same machine. In practice one has a 1006 g shot weight and a 570 × 570 mm tie-bar opening, and the other has neither — it simply carries a similar clamping force with a smaller injection unit and a narrower platen.

Price is the last thing you compare, not the first. Below are the twelve specifications that decide whether a machine will actually run your mould, at your cycle, for the next ten years. Ask for all twelve in writing.

The 12-point checklist

1. Shot weight — in grams, with your cushion

Give the supplier your preform weight × cavity count, and ask for the machine's rated shot weight in grams. A 16-cavity mould running a 33 g preform needs 528 g per shot; a 48-cavity mould at the same weight needs 1584 g. If the machine tops out near your requirement, you have no room for process variation and no room to grow.

2. Screw diameter and screw design for PET

Screw diameter determines shot volume and plasticising rate — on a typical preform range this runs from 50 mm to 70 mm. Ask specifically whether the screw is designed for PET, and what the L/D ratio and compression ratio are. A general-purpose screw repurposed for PET will give you inconsistent melt and degraded material.

3. Clamping force — and the unit it is quoted in

Check whether the number is kN or metric tons. 1700 kN, 2300 kN and 2700 kN appear across a normal preform range — that is roughly 173, 234 and 275 tons. A quote that says "270 ton" without a kN figure is a quote you cannot compare.

4. Space between tie bars

This is the dimension that decides whether the mould fits at all. Typical values run from 460 × 460 mm on a small machine up to 570 × 570 mm and beyond on a larger one. If you already own the mould, measure it first and put the number in the enquiry.

5. Mould thickness range (minimum–maximum)

Ask for both ends of the range, for example 200–550 mm. A mould that is thinner than the minimum cannot be clamped; one thicker than the maximum simply will not go in. This is the most common cause of a machine arriving and not being usable.

6. Toggle stroke and ejector stroke

Toggle stroke must open the mould far enough to release the preform. Ejector stroke must push the preform off the core without distortion. Both are stated in millimetres on a proper specification sheet — 540 mm toggle stroke and 150 mm ejector stroke, for instance, on a 2700 kN machine.

7. Injection pressure and injection rate

PET needs to be injected fast and hard. Ask for injection pressure in MPa and injection rate in g/s, not just "high speed". Roughly 160 MPa is a normal figure for productive preform work. An under-specified injection unit shows up as short shots, haze and visible flow lines.

8. Plasticising capacity (g/s)

The injection unit must melt the next shot while the mould is cooling the current one. If plasticising capacity is too low, the machine cannot reach the cycle time it promises — the barrel becomes the bottleneck, not the mould.

9. Drive type and motor power

Confirm whether the machine is hydraulic, servo-driven or hybrid, and what the motor power is in kW. A hydraulic machine and a servo machine with the same clamping force can differ by a large margin in energy cost per thousand preforms. Ask for the servo option to be quoted separately so you can model the payback rather than guess it.

10. Control system, language and safety

Ask which controller is fitted, whether the HMI supports your operators' language, how many parameter sets can be stored, and what the safety architecture is. Look for closed-loop temperature control, mechanical and electrical safety interlocks on the operator side, low-pressure mould protection, and automatic centralised lubrication. These are the differences between a machine that a technician can dial in and one that a technician has to fight.

11. Scope of supply around the machine

A preform line is not just the injection machine. Confirm in writing what is included:

• Preform mould, and whether it is hot-runner and valve-gated

• Dehumidifying dryer and hopper loader sized for PET (drying at 160–180 °C for 4–6 hours to below 0.005 % moisture is the standard requirement)

• Mould temperature controller and chiller

• Robot or take-out device, conveyor, and any post-cooling

• Spare parts list

A machine quoted without the dryer and the mould temperature controller is not a cheaper machine — it is an incomplete one.

12. Certification, handover and service

Finally, the terms that decide what happens after the container arrives:

CE certification

• or the certification your market requires

• Warranty period and what it covers

• Installation, commissioning and operator training — included or extra?

• Lead time, payment terms and packing

• Who supports you locally, and what happens at 2 a.m. when the machine stops

Ask the last question directly. "Do you have a service team in my region, and what is the response time?" is a fair question, and the answer tells you more than the price sheet does.

What good looks like

Send this twelve-point list to every supplier you are considering. The suppliers who answer it completely, in writing, with units and ranges, are the ones who will also answer you during an installation problem. The ones who reply with a price and a photo are telling you something useful too.

efficent builds PET preform injection moulding machines together with the moulds that run in them, and tests them as a matched set before shipment. Send us your preform weight, cavity count and target output, and we will tell you which model the job needs — including when the answer is a smaller machine than you expected. 

Sources

• efficent PET series technical parameters (machine manufacturer specification sheet) — shot weight, clamping force, tie-bar spacing, mould thickness, strokes, motor power, injection pressure.

• Alpine Mold,

PET Injection Molding Guideline: A Complete Guide for Engineers and Manufacturers

, published 2025-08-01 — PET drying conditions, screw and machine requirements, preform mould temperature.

• Cavity Mold,

PET Preform Injection Molds: Design and Process Basics

, updated 2025-09-01 — preform approval criteria including weight, neck/gate dimensions and wall distribution.