With its unique properties, including longevity and weather resistance, plastic is now an essential material used in the production of countless consumer and commercial goods. Statistics show that global production of plastics has increased from just 100 million metric tons in 1989 to nearly 400 million metric tons in 2021. Not all plastic products are solid, however. Many are, in fact, hollow. When creating hollow plastic products, manufacturers often use a process known as dip moulding.

What is dip moulding?

Think of a pair of pliers. Specifically, the cushioned handles. They were made with dip moulding to make the grip comfortable, while protecting the metal underneath. Plastisol, also known as liquid PVC, is an ideal material to be used in the dip moulding process. This is largely because it is a flexible material which is soft to touch, creating a comfortable handle or grip. Dip moulding is a process that either coats metal parts with polymers or creates hollow plastic parts. You will find applications of dip moulding everywhere, from petrol pump handles and chair armrests to medical devices.

What does the process look like?

Dip moulding is a manufacturing process similar to candle making in its methods. Heated metal moulds are dipped in a tank of liquid material. This material may be heated or at ambient temperature. The moulds are extracted and then put through a baking process to cure the material before the part is then stripped from the mould. Once baked the material does not return to the liquid state.

Why is dip moulding ideal for Plastisol?

As with candle making, the mould may be dipped several times to build up layers. The mould may also be dipped into different materials to create different effects. For example, handles for hand tools may be dipped first in a hard material to provide a tight fit and durability, and then into a softer material for a comfortable grip.

Why should you consider it?

Dip moulding is both a cost-effective and time-efficient process. Some of the advantages of using this process are….

• It’s more cost effective than other processes – Dip moulding is simple and inexpensive. It has low tooling costs, a fraction of injection moulding, and competitive production costs. That’s because the moulds are single-sided and geometrically less complex than say, moulds made for injection moulding, so they’re faster to make.

• It’s easier to create prototypes – Prototyping is also cost effective for this reason – any changes to the mould are relatively easy and fast to make. All of this contributes to a quicker end-to-end process and shorter delivery times to the customer.
• It’s ideal for mass production – this is due to the low production costs of the mould.
• Products can be manufactured in various colours and textures –Because dip moulding is so precise, creating intricate or complex parts isn’t a problem. Finishes such as gloss and matt are available and wall thickness can be easily controlled.
• It’s extremely precise – When using plastisol with dip moulding techniques, the inside of a part comes out as a precise negative of the mould. This is because plastisol follows the details of the dipping mandrel (the equipment that’s dipped into plastisol to form the dip moulded parts) exactly. It not only shares the same shape, but also the same texture as the mould.
• Latest innovation – Our dip moulding plastisol range can be readily formulated and converted intoPB Protect antiviral plastisol. This means that any of our plastisol products can be formulated with both antimicrobial and antiviral protection which is effective for the lifetime of the product.

Have you considered using dip moulding for your plastisol products?

If you are interested in learning more about dip moulding and the necessary plastisol products, then please do request a brochure, or get in contact with me directly mark@polyblend.co.uk

How much do you know about the dip moulding process?

Dip moulding and coating is a plastics process that, while used commonly on many types of products that include everything from medical devices to hand tools to fuel pump handles, remains largely unknown to many plastics engineers and product designers.

Yet, dip moulding and coating using a variety of liquid polymers offers many advantages and, in certain applications, can even be an excellent alternative to the injection moulding and extrusion processes.

How does the dip moulding process work?

Dip moulding is a special technique where a mould is dipped into liquid plastisol. The plastisol coating is ‘picked-up’ by the residual heat of the mould and cured by heat fusion and then blown from the mould.

The main advantage is that the mould is only a fraction of the cost compared to the tooling costs of other production methods, even for the production of large volumes.

Here’s a step-by-step guide of the dip moulding process we use at PolyBlend for our custom formulated products.

Below, the dip moulding process is explained step by step.

Why choose dip moulding?  The step-by-step description above gives a basic overview of the dip moulding process. Dip moulding is a special technique where a mould is dipped into liquid plastisol. The plastisol coating is ‘picked-up’ by the residual heat of the mould and cured by heat fusion and then blown from the mould.

The main advantage is that the mould is only a fraction of the cost compared to the tooling costs of other production methods, even for the production of large volumes.

1. The mould

The tool(s), also called moulds, are specified to produce the end article. The tools are mounted on a special frame or plate.

2. Heating the mould in the oven 

The tool is preheated in an oven until it has reached a specified temperature. The combination of temperature and dip time (known as dwell time) determines the eventual wall thickness, i.e. how thick the coating of the finished article is.

3. The heated mould is dipped in liquid vinyl/plastisol

After preheating, the mould is transported to the dip tank. The dipping speed determine by, among other things, the shape of the mould and its length. Sometimes, the dipping speed must be varied during dipping to produce a product that is as uniform as possible.

The control, skill and experience delivers consistent and repeatable mouldings.

4. Curing the dipped product in the oven

The dipping process stops at a pre-determined set point. The wall thickness increases as time advances. This can vary from several seconds to up to 2 minutes. Afterwards, the mould is removed from the vinyl/ plastisol at a specified speed. The dip frame is then automatically transported to another oven in which the product cures completely.

5. Cooling the dipped mould in water

After curing, the complete dip frame including dip moulded products is cooled in water to allow the products to be removed from the moulds. It is not desirable to cool the product completely because the “residual heat” it contains makes it easier to release if from the mould. For complex shapes like bellows, this is of course very important.

6. The product is blown off the mould

The dip moulded products are released from the moulds manually or using compressed air.  The use of an FDA approved releasing agent speeds up this process.

Summary

In summary, dip moulding provides a huge number of advantages. And whilst aware and actioning on sustainability within the industry, we want to ensure that all processes are safe, the article is compliant to the environment it is intended and process efficient in manufacture so to produce minimal waste to the customer.

If you are interested in learning more about dip moulding and the necessary plastisol products, then please do request a brochure, or get in contact with mark@polyblend.co.uk

FAQ

What is dip moulding?

Dip moulding is a process in which a pre-heated metal form or tool is dipped into a coating material to create a PVC or Acrylic part. When a thorough coating is achieved, the liquid is solidified, and the complete article can be removed or trimmed.

Can handles or grips be made?

At PolyBlend we have a formulating process which allows products like handle grips to be comfortable yet highly durable. Handle grips serve many purposes including providing comfort for the user, helping to support weight, and offering improved traction. All elements increase ease of use as well as safety.

Can soft or grippy handles be made?

Soft grips also often provide anti-vibration properties for equipment, which helps with noise, disruption, and harshness and prevent injury or harm. We create many of our handle grip formulations from years of experience and working very closely on the discovery and development process. 

How durable is the dipped product?

The hermetically sealed surfaces stand up to harsh conditions including strong detergents, chemicals, heat, hazardous environments. This makes dip moulding the perfect solution for exercise and medical equipment.

What products can be produced?

Dip moulding is an extremely flexible process and can be used with a wide variety of materials. Everything from endcaps to tool handles, automotive bellows to custom surgical and medical parts and components for hospital use can be created using dip moulding products.?

How do you ensure dip moulding quality?

Every batch manufactured goes through a stringent quality control process. As per agreed customer specification requirements, each sample will be tested under conditions to replicate the specific dip process as agreed at the development stage.