What Are the Types of Injection Molding Machines?

Four Ways to Classify Injection Molding Machines

Injection molding machines are classified in several overlapping ways. The drive system describes how the machine generates motion and force. The clamp design describes how the mold is opened, closed and held shut. Orientation describes whether the machine is horizontal or vertical. Application describes the specialized configurations built for packaging, preforms, multi-material parts, PVC and very large parts.

A single machine belongs to one category in each group. For example, a servo-hydraulic, toggle-clamp, horizontal machine configured for thin-wall packaging. Understanding each classification helps you compare offers and choose the configuration that suits your part, mold and output.

Types by Drive System

Drive choice affects energy use, precision, purchase price and maintenance. Hydraulic and servo-hydraulic machines handle high forces, core pulls and large molds easily. All-electric machines excel at repeatability and cleanliness but cost more per ton and are less common at large tonnages. Servo-hydraulic machines cover the widest range of applications at a balanced cost of ownership.

Conventional hydraulic

A constant-speed electric motor drives a fixed or variable-displacement pump. Robust and powerful, but the pump runs continuously, which raises energy use and oil temperature during cooling and idle phases.

Servo-hydraulic

A servo motor drives the pump and changes speed with demand, delivering oil only when the cycle needs it. It keeps hydraulic force and durability while cutting idle energy use and reducing oil heating. This is the most widely used drive for general-purpose and packaging machines today.

All-electric

Each axis (injection, plasticizing, clamp, ejector) is driven by its own servo motor and ball screw or belt. Very repeatable and clean, with low idle consumption. Most common in small and medium tonnages for precision, medical and electronics parts.

Hybrid

Combines electric and hydraulic axes, for example electric screw rotation with hydraulic injection and clamp, or an electric clamp with a hydraulic injection unit. Used where a specific axis benefits from electric precision or parallel movement.

Types by Clamping System

Toggle machines dominate up to medium-large tonnage because they are fast and economical. Above roughly 6,000 to 8,000 kN, two-platen machines become attractive for large molds that need long opening strokes and wide platens, such as bins, pallets, crates and automotive bumpers and panels.

Toggle clamp

A hydraulic cylinder or servo motor drives a linkage that multiplies force and locks the mold. Toggles give fast, smooth movement and are energy efficient. The five-point double toggle is the standard in small and medium machines.

Direct hydraulic clamp

A large central cylinder applies clamping force directly. Force is easy to adjust and evenly distributed, but large oil volumes are needed and movement is usually slower than a toggle.

Two-platen clamp

Short clamping cylinders, often integrated in the fixed platen, apply force through the tie bars, which are locked to the moving platen by split nuts. Removing the toggle and rear platen shortens the machine and increases mold opening space, which makes two-platen designs efficient at large tonnage.

Types by Orientation: Horizontal and Vertical

Horizontal machines open the mold horizontally, and parts fall or are removed by robot under gravity. They are easy to automate, suit high output and make up the large majority of installed machines.

Vertical machines open the mold vertically. Gravity holds inserts in place, which suits insert molding and overmolding of metal parts, cables and electronic components. Rotary or shuttle tables allow loading of inserts while the previous cycle runs. Vertical machines are typically smaller in tonnage and are chosen for insert work rather than high-volume packaging.

Types by Injection Unit Design

Most modern machines use a reciprocating screw: the screw rotates to melt and meter the material, then moves forward as a ram to inject it. This single-stage design gives good melt quality and accurate shot control for the vast majority of thermoplastics.

Two-stage or screw-plunger units separate the jobs. A screw plasticizes the material continuously and feeds it into a separate shooting pot, from which a plunger injects it. This allows plasticizing to continue during injection and holding, which helps with very large shots and some high-output preform applications. The trade-off is a more complex melt path that must be purged carefully during material changes.

Within reciprocating-screw machines, the injection unit size is itself a key variable. Many manufacturers offer several screw diameters on the same clamp so the shot volume and injection pressure can be matched to the part. On the HWAMDA M8SII series, A, B, C and D injection unit options are available per model, and the DP multi-material series pairs two or three units on one clamp, for example the HMD-DP410 with a 785 g A unit and a 932 g B unit (PS).

What the Differences Mean in Production

Types by Application

High-speed thin-wall machines

Built for cups, food containers, lids and IML packaging. They combine high injection rates, fast clamp movement, rigid platens and short dry cycles to fill walls below about 0.7 mm in fractions of a second.

PET preform machines

Configured with a long L/D PET screw, high plasticizing rate and a clamp suited to multi-cavity hot runner preform molds with post-mold cooling.

Multi-material machines

Two or three injection units feed one mold to produce two-color or two-material parts, such as soft-touch handles, multi-color closures and household items.

PVC machines

Equipped with low-compression screws, corrosion-resistant barrels and precise temperature control to process rigid PVC for pipe fittings without degradation.

Large-tonnage machines

Usually two-platen designs with large platens, long strokes and high shot capacity for logistics, automotive and industrial parts.

Comparison of Injection Molding Machine Types

Which HWAMDA Series Fits Each Type

HWAMDA builds machines across servo-hydraulic general-purpose, high-speed thin-wall, two-platen, multi-material and application-specific configurations. Each machine is assembled in Ningbo with CNC-machined key components and is production-tested before shipment.

How to Choose Between Machine Types

Start with the application. If the part is thin-wall packaging, a PET preform, a multi-material part or a PVC fitting, a specialized configuration will outperform a general-purpose machine. For everything else, a servo-hydraulic toggle machine is usually the most versatile and economical choice, with a two-platen design for large molds.

Then confirm the size with clamping force, shot size and mold fit calculations, and check the full cell: robots, IML, dryers, chillers and mold temperature controllers. HWAMDA's configuration consultation reviews part, mold and utilities together to recommend the series and model that match your project.