A vertical injection moulding machine opens and closes its mould up and down instead of side to side. The lower mould half faces upward, so metal inserts, pins or cable ends placed in it stay put under gravity while the mould closes. The main types of vertical moulding machine differ in injection direction (vertical clamp with vertical or horizontal injection) and in table design (fixed, sliding or rotary). They suit insert moulding, overmoulding and small to mid-size parts where loading by hand or robot is part of every cycle.
Key Takeaways
- Vertical clamping lets gravity hold inserts in the lower mould half, which is the main reason to choose one.
- Injection can be vertical through the mould or horizontal into the parting line.
- Sliding and rotary tables let the operator load one lower half while the other is moulded.
- Parts do not drop clear, so plan removal by hand or robot from the start.
Why is the clamp vertical?
The clamp is vertical so the lower mould half faces up like a table. Inserts, pins, cable ends or pre-moulded parts can be placed into it and stay located while the top half comes down. On a horizontal machine, the same insert would hang on a vertical mould face.
That changes how inserts are held. On a vertical mould, a brass bush can sit over a core pin with no magnet or spring clip. Gravity does not lock it in place, though; the pin fit still has to be close, or the insert can lift and float in the melt.
Moulding metal in has its own costs. A PlasticsToday summary of DuPont insert-moulding advice lists inserts that float or damage the mould, flash in internal threads, slow loading and costly rejects among the disadvantages, and says moulding in is often considered a last resort where pressing, snap-fitting or ultrasonic insertion into a moulded part would do.
The trade-off is part removal. On a horizontal machine, parts can drop out between the platens. On a vertical machine, the moulded part sits in the lower half, so someone or something has to lift it out every cycle.
What types of vertical moulding machine are there?
There are two main splits. By direction: vertical clamp with vertical injection, where the nozzle enters through the mould, and vertical clamp with horizontal injection, where the nozzle meets the parting line from the side. By table: fixed, sliding (shuttle) with two lower halves, or rotary with two or more.
Types of vertical moulding machine and where each fits
| Type | How it works | Typical fit |
|---|---|---|
| Vertical clamp, vertical injection | Nozzle enters from the top or bottom through the mould | Centre-gated parts, overmoulding on pins and inserts |
| Vertical clamp, horizontal injection | Nozzle injects into the parting line from the side | Cable overmoulding where the cable lies across the parting line |
| Fixed table | One lower half; load, mould and unload in sequence | Short runs, trials, large inserts |
| Sliding (shuttle) table | Two lower halves slide in and out under one top half | Loading while the other half is moulded |
| Rotary table | Two or more lower halves on a turntable | Several stations for loading, checking and unloading |
The table can matter more than the clamp for output. A cost-model guide from aPriori sets it out: a shuttle table holds two moulds moving side to side, a rotary table holds two or more and rotates, and either lets pick and place happen on one mould while the other is injected. Its default tooling is two lower halves plus one upper half, and that choice drives tooling cost. The insert moulding article in this series shows the cycle effect in numbers.
Injection direction follows the part. If a cable has to leave the mould sideways, injecting into the parting line keeps the nozzle out of its way; if the part is round and gated at the centre, injecting through the mould is the natural choice.
Which jobs suit a vertical injection moulding machine?
Vertical machines suit parts with something placed in the mould before each shot: brass bushes, threaded inserts, terminals, pins, cable ends, needles and pre-moulded parts for overmoulding. They also suit short runs of small parts where an operator loads and unloads by hand anyway.
Electrical accessories are a clear Indian example. Plugs and socket-outlets are made to IS 1293 and switches to IS 3854. The BIS blog on these standards lists tests for earthing, shock protection, resistance to abnormal heat and fire, mechanical strength, and normal operation, where a plug is inserted and withdrawn 10,000 times. Pins and terminals held in the moulded body have to stay put through all of that.
The full range of products, from needle hubs to cable ends, is in the applications article in this series.
What are the limits of a vertical machine?
Vertical machines are taller, need parts lifted out rather than dropped, and need one lower mould half per table station, which adds tooling cost. For parts with no inserts, a horizontal machine with parts dropping out is the simpler route.
Safety needs thought too, because the operator reaches into the mould area every cycle. Guarding, light curtains or two-hand controls, and interlocks on table movement have to be designed around that loading pattern, not added later.
My view: buy a vertical machine for the insert, not for the floor space. If nothing goes into the mould before the shot, start with a horizontal machine; the side-by-side comparison is in the horizontal vs vertical article in this series.
What should you send before choosing a vertical machine?
Send the part drawing, the insert drawing and how many inserts go in each shot, the material, the number of cavities, and whether loading will be by hand or robot. With those, a supplier can suggest the clamp, injection direction and table type together. See the vertical injection moulding machine range.
Frequently Asked Questions About Vertical Injection Moulding Machines
Is a vertical injection moulding machine hydraulic or electric?
Clamp and injection can be hydraulic, fed by a fixed-speed or servo-driven pump, and some machines use electric drives for some movements. The drive changes energy use and control, not the reason for going vertical. Ask which drive each movement uses and what power is measured on a cycle like yours.
Does a vertical machine take up less floor space?
It can take less floor area than a horizontal machine of similar tonnage because the clamp stands upright, but it is taller. Allow for headroom, the operator position, insert trays, a parts bin or conveyor, and the swing of a rotary table when you plan the layout.
Can a vertical machine run parts without inserts?
Yes. It moulds plain parts like any other machine, but parts must be picked out of the lower half because they cannot drop clear. That adds handling time or a robot. If a job will never need inserts, compare a horizontal machine first and keep the vertical for jobs that do.
What is a C-frame vertical machine?
Some vertical clamps use a C-shaped frame instead of tie bars, leaving three sides of the mould open for loading. Tie-bar designs carry the clamp load through four bars. Ask which design the machine uses, how it controls platen deflection under full clamp, and how much access you get for loading.
Who loads the inserts on a vertical machine?
Either an operator or a robot. Manual loading suits short runs and frequent part changes; robots suit long runs with a steady, consistent insert supply. Robots need inserts that arrive the same way every time and fixtures to present them, and both need guarding that matches the loading pattern.
Related Articles
- How Does Insert Moulding Work on a Vertical Machine?
- Horizontal vs Vertical Injection Moulding Machines: Key Differences
- Important Specifications to Consider Before Buying a Vertical Machine
- Applications of Vertical Injection Moulding Machines
Sources & References
- PlasticsToday (IMM), summarising A. Miller, DuPont: Design and material advice from the pros, Part 3: Insert molding essentials (Sept 2005)
- aPriori: Cost Model Guide: Insert Injection Molding Options
- BIS Blog, N. Agarwal: Standards for Plugs-Socket-Outlets and Switches (Feb 2023)
- Plastics Technology, J. Williams (RJG): Clamp Tonnage: More Is Better...Right? (May 2017)
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.
