Depending on the material, geometry, requirements and quantity, a plastic component can be manufactured in various ways. It is therefore not just a question of which process is technically feasible, but which offers the most appropriate solution for the task at hand.
HAMCO utilises a range of manufacturing processes for the production of technical plastic components, as well as processes for coating suitable components. In consultation with its customers, the most suitable process is selected on the basis of the technical requirements, the desired properties, the component geometry and the required quantity. In doing so, technical feasibility and cost-effectiveness are given equal consideration.
On the following pages, you will learn how the various manufacturing and production processes work, what their distinctive features are, and what possibilities they offer for the production of technical plastic components.
Soft PVC is particularly suitable for processing by extrusion, injection moulding, dipping, coating, thermoforming, thermal bonding and solvent-based bonding. Due to its softness and temperature sensitivity, PVC requires specific manufacturing process parameters to prevent thermal decomposition of the material.
Our processes in detail:
Injection moulding: Soft PVC is melted in the barrel of an injection moulding machine (approx. 160–200 °C) and injected into moulds to produce precise and complex moulded parts (e.g. seals or plugs). Find out more about PVC—Injection moulding process
Dipping & Coating: Metals or other substrate materials suitable for heating in a furnace are dipped into liquid soft PVC (plastisol) to produce durable, shock-absorbing coatings or flexible dipped parts. Find out more about the Immersion process and the PVC coating
Joining & Bonding: PVC parts can be joined thermally (e.g. hot-air welding) or chemically (bonding). Special adhesives suitable for use with plasticisers are used for this purpose.
The key difference lies in the method and precision of the moulding process: In injection moulding, molten, hot plastic is forced under high pressure into a closed, cooled hollow mould and, once cooled, is demoulded as a finished moulded part with excellent accuracy in reproducing the internal and external contours. In the dip-moulding process, a pre-heated component or heated dip mould is immersed in an unheated bath of liquid PVC plastic (plastisol) and remains in the dipping tank until, without the application of pressure, a sufficient amount of material has adhered to the metal surface, which is wetted by the liquid and cooling slowly. The internal contour exhibits good accuracy, whilst the external contour tends to be rounded and less precise.
At the PVC dipping and coating processes Gelling, or the gelling process, refers to the transition of liquid PVC plastisol into a solid, rubber-like state when exposed to temperatures of 80°C or above.
When cold, the finest PVC particles, plasticisers and other formulation components are evenly and loosely distributed within the liquid-paste-like PVC plastisol. When a highly heated workpiece is immersed in the paste, contact with the hot surface causes the PVC particles to absorb plasticisers, swell and adhere to the hot surface. This very quickly forms a gel-like layer on the surface of the metal part as it cools slowly. The physical and mechanical properties of PVC grades are achieved following a final heat treatment at temperatures above 150°C in the furnace.
The task at hand is the key difference when comparing the two manufacturing processes. Whilst in the Coating where a component that has been heated beforehand is coated with a functional layer (e.g. corrosion protection, electrically insulating coating) by immersion in a plastisol dip bath (dip coating) and the coating remains on the component, the aim of the Immersion process of a preheated moulded part (dip moulding), and, once the material has gelled, to be able to remove a functional part (cover cap, paint protection or impact protection) from the dip mould and use it for any components.
When applying a PVC coating to metal components, care is taken to ensure that they are as free as possible from grease and oil-based contaminants. The components are heated in an oven and then immersed in a tank filled with plastisol. Under the influence of heat, the PVC gels and fuses to form a continuous, firmly adhering plastic layer which, following the final heat treatment, protects the component against corrosion and mechanical stress.
Further information for buyers, technicians, design engineers and developers is available on the product page PVC coating and rubberising Ready.
The coating can be applied primarily to metals (steel, structural steel, stainless steel, aluminium, copper, brass), as well as Glass and ceramics, as well as some heat-resistant plastics. In industrial practice, however, it is predominantly metal parts that are used in the PVC dipping process coated, because they can withstand the required process temperatures and store the thermal energy needed for the gelling process.
The suitability of galvanised or powder-coated metal parts for Coating with PVC This must be tested in practice, as the quality of the pre-treatment is also crucial to the quality of the coating. As a powder coating acts as a bonding agent between the metal and the PVC layer, the process parameters for the PVC coating should be determined on uncoated raw parts. Visible discolouration on uncoated areas of galvanised parts, as well as possible blistering on poorly powder-coated metal parts, cannot be entirely ruled out.
Some high-temperature-resistant plastics, such as PEEK and PET, can be coated under certain conditions. Even if the softening temperature is above 200 °C, the wall thickness in the area to be coated on the plastic parts must be sufficiently large to store and slowly release the thermal energy required for the PVC particles to gel on the moulded part’s wall.
Yes, a second layer of PVC in a different colour can be applied using the dip-coating process. This process is used when multi-coloured layers, decorative effects or additional functional layers of varying hardness are required.
First, a component or a moulded dip mould is dipped into the PVC plastisol containing the first colour, and the first layer is allowed to gel to the desired thickness. Depending on the process, the cooled component or dip mould is either reheated to a lower temperature or maintained at a defined temperature whilst the process is ongoing. This is followed by a second dipping process in the plastisol using a different colour. The second layer gels onto the surface of the existing first PVC layer. During the final heat treatment, both layers are thermally bonded together.
Completely dipping the item in a second colour usually results in the first colour being covered. Two-colour designs are therefore often created by partial dipping or by covering (masking) specific functional areas. Examples of applications include tool handles with a coloured grip zone or protective caps subject to mechanical stress, which allow wear to be detected in good time.
Yes, soft PVC can be welded. It is a thermoplastic and softens or becomes fusible when heated, allowing two parts to be joined by material bonding. Most commonly, the joint surfaces are heated with a hot wedge and then pressed together under pressure. However, caution is advised: overheating the joints can lead to the thermal decomposition of PVC. This decomposition releases, amongst other things, hydrogen chloride (HCl), which is why effective extraction is essential. As the bead-like joint formed during welding requires mechanical finishing, we recommend bonding the parts together.
Soft PVC is generally easy to bond, although the choice of adhesive is more important than with rigid PVC, as the plasticisers it contains can adversely affect the bonded joint. In most cases, two soft PVC parts are bonded using solvent-based PVC adhesives. It is crucial that the adhesive is suitable for PVC containing plasticisers, so that the joint remains permanently flexible and strong at the bonding point once the solvent has evaporated. In contrast to the welding of soft PVC parts, when Bonding only a very slight ridge-like thickening at the joint.
Yes, both soft PVC dip-moulded parts and PVC-coated components can, in principle, be used in the pad printing process can be printed on. The 1- or 2-component ink system is perfectly suited to the surface characteristics of the glossy, smooth standard types, as well as to the matt, pearlescent finish of the two special types of soft PVC and the plasticisers they contain. No pre-treatment (e.g. cleaning, flame treatment, corona or plasma treatment) is required for our PVC products.
Yes, undercuts can often be achieved in soft PVC dip-moulded parts, and indeed much more easily than in many injection-moulded parts. Light to moderate undercuts, or so-called forced demoulding with thin walls, are often achievable without difficulty in soft PVC dip-moulded parts, as the material is sufficiently flexible and elastic. When being removed from the dipping core, the dipped part – which is fitted with a locking groove or a circumferential bead – can be temporarily deformed (stretched) and subsequently returns to its original shape.
In the case of pronounced undercuts, such as those found in a bellows, we have to determine the geometry based on material hardness, wall thickness and Plunger core design be assessed.
Large and small quantity requirements Direct processing
Large and small quantity requirements
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