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Making plastic products

We briefly describe here our production methods. Understanding our process could make it easier for customers to work with us effectively. Of course, if you are a new customer, tell us about your particular industry constraints or requirements. If you would like to know more, of if you have suggestions for the content of this article, please let us know!

Steps in the production of a new plastic item:

Let's assume a typical injection moulded key ring toy. We will agree with you at an early stage on the procedure and such details as hold points at critical steps. The usual steps are:

1) Design of the master figure:
Clay (plasticene) model made by model maker > view, comments & approval by Chi Hong (hold point) > Rubber mould > Plaster model (final shape & all details) > submission to Client for approval and any modifications to be agreed (hold point)

2) Making the master mould:
Launch mould making > Chi Hong factory manager responsible from receipt of plaster mould to completion of the production moulds including all necessary production details such as the ingate and main gallery, branches and details for air removal, provision of wires for bendable items etc.>

3) First batch samples:
Submission to Client for approval of a first batch trial run with full painting and finishing details including packaging > agree any minor modifications to painting or packaging (hold point)>

4) Mass production.


plaster model

More background information below:

What is plastic?

Plastic is a polymer or chain of molecules with strings of carbon and other elements, made from petroleum by linking chemical reactions. There are so many different types with varying properties. Bio-based plastics are being researched and developed, but are not yet a feasible option in the toy business.

Thermoplastics such as Acrylic (Perspex), Acrylo-nitrile (Nylon), Polyethylene (Polythene), Polyvinylacetate (PVA), Polystyrene (PS) and Polyvinylchloride (PVC) soften with heat and harden when cold. They can be recycled and re-used repeatedly. We use thermoplastics in our products.

Thermosets such as Bakelite, Epoxy, Melamine, Polyester and Polyurethane are cured or hardened by heat, and cannot be re-used like thermoplastics.

Some plastics are spun into fibres, made into yarns and used for weaving into textiles or made into ropes; some can be sprayed as a coating, used as a glue, or used in paint. Plastics are used in toys because they are easy to shape and colour, they can be made soft or hard, flexible or stiff, they are good insulators, do not rust, are lighweight, cheap and durable.

Our products are often made from Polyethylene (PE) as it suits our products, methods and machines. We use other plastics according to the product requirements. PE is a relatively environmentally friendly plastic. There are different qualities, densities and types. For some purposes we can use recycled raw materials.

Additives are used in the plastic raw material to give various properties. Different plastics can contain all sorts of additives such as plasticisers or softeners, flexibility agents, fillers, reinforcement, pigments, flame retarders, antioxidants, blowing agents, lubricants, heat stabilisers, UV stabilization etc. etc. We often add colouring to the plastic mass as necessary.

Although we are aware of the regulations in most countries, it is always prudent to specify to us any special requirements or compositions, specific to the use of the product in your country, and whether any special testing, analysis or certification is required.




How is plastic shaped?

There are many different processing techniques commonly used in the toy and plastics industry. Most involve the use of a mould. Our factory uses the first two moulding methods.*

*Injection moulding: Plastic beads are melted under heat and shear energy and injected under pressure into a steel mould to give the required shape. The mould cavity is essentially a negative of the part being produced. Our factory uses this method predominantly.

*Blow moulding: Plastic material is forced into a closed mould and compressed air is used to blow a "bubble" inside the plastic. The plastic swells out like a balloon until it fills the mould and the required shape is obtained. We make dolls, soft and hollow toys using this method. (Plastic bottles can also be made this way.)

Rotational moulding: Plastic material is placed in a mould over a burner, and the mould is rotated to achieve a uniform wall thickness. Large hollow toys, water tanks and barrels can be made this way.

Extrusion: Hot molten plastic is forced through a nozzle to make pipes, tubes, jointing strips such as used in the building industry; and also large sheets that can be used later in thermoforming.

Blow extrusion: This is used for making plastic bags and films. An extruded tube with a sealed end is blown up like a balloon while still hot, stretching the plastic to make it thin.

Thermoforming: The plastic sheet is heated to near its softening temperature, and then pressure is placed on it with a male and/or female mould to produce a shape. This method is used to make trays, cups, masks and boards.

Vacuum forming: Sometimes pressure and vacuum are used in the thermoforming process and maximum uniformity of thickness and strength can be obtained. Packaging for biscuits and confectionery, cosmetics, disposable cups and containers for yoghurt can be made this way.

Slush moulding: This involves filling a hollow moulding with a solution of plastic material, heating the mould to gell an inner layer or wall of material in the mould, and then inverting the mould to pour out the excess liquid material. After cooling the finished part can be removed. This is used to make hollow objects.

Dipping: The mould is dipped into a plastic solution and the coating is fused to make the item. Soft flexible toys such as balloons, handlebar grips and flexible covers can use this technique.

Fabrication: Plastic sheets can be fabricated into tanks, acrylic signboards, and other industrial articles, by cutting, folding or bending and glueing.

Our production process.

We assume that an entirely new product is to be created.

Of course, if you choose to use one of our existing products the delivery will be faster.

Or you may wish to have a logo or message printed on one of our existing items. This is also very quick, and we just need to allow for making samples and sending them to you for approval.Some of our products have an ideal shape for block-printing (football jersey, heart, smiling face, paperclip...)

It is best to ask us about delivery times as our workload can vary according to the time of the year. The order quantity is also a factor. We can usually deliver large orders in phases to suit your schedule and suitable shipping volumes. It is prudent to allow a minimum 5 or 6 weeks for shipping each delivery from Hong Kong to your nearest port. We can also air freight the first production batches for you if time is short.

It is important to to consider:

Manufacturing process: Blow moulding minimises the material quantity used, and gives a soft, flexible, light and cheap product that can be very cute. However if it needs to be painted care needs to be taken to ensure the paint sticks. Injection moulding can be used to give complex shapes and details, and is easier to paint and finish.

Material: What is the use of the product? Contact with food items? Child's toy? Flexible item? Bendable item? Hard or soft plastic? Eraser? These factors will affect the choice of the plastic type.

Size: If too large there are more material costs, more weight and volume to transport. If the object is very small, and there is a lot of detailed painting in several colours, then finishing is difficult and quality is difficult to maintain. Certain sizes may be dangerous for small children (swallowing). If it is a capsule item, then its size must just fit the capsule for which it is intended.

Shape: The object must have a shape that allows it to be removed from the mould. Usually the mould is in two half-pieces with a flat interface at the joint. Re-entrant or undercut shapes make it difficult or impossible to remove from the mould, and two separate moulds may be needed, which will increase the costs. Sometimes a small and acceptable change to the shape will solve such problems. If a separate piece is nevertheless required, the piece will be glued, so agreement on the type of fixing and glue is needed. (Sometimes a flexible plastic will allow de-moulding when it could seem very difficult.)

If the item is for a key chain then a loop for attaching the chain and ring will be incorporated in the mould. Very often a hole will be placed in the bottom so that a pencil topper version can use the same mould, and the volume of material is slightly reduced.

Painting and colours: If there is a predominant colour then this will be applied in the plastic mass. Glitter and other effects can also be applied. Spray painting can be used for rainbow or other effects.

Incorporated items: Is there any small objects to be built in, like lights with battery, metal attachments, provision for screws to fix parts?

For any comments, suggestions or enquiries, you are welcome to email us at chihongtoys@biznetvigator.com