Roto-moulding for custom projects

January 6, 2015

Established in 1896 and a leader in the rotational moulding industry since 1976, Excelsior has undertaken a huge range of custom rotational moulding jobs, creating an array of products, ranging from simple water floats through to highly complex products requiring significant levels of expertise, such as anti-tank missile cases for the army.

Rotational moulding is an extremely versatile process for the manufacture of a vast range of plastic products and components; that’s why Excelsior has used it to bring its customers’ plastic products to life for more than 40 years.

More and more businesses are choosing rotational moulding to produce their custom moulded plastic parts because it’s often the most cost-effective, consistent and flexible process for small to medium sized batch runs.

Rotational moulding offers real advantages to custom clients over injection and blow moulding, which include:

Low start-up costs: Roto moulding tools cost a fraction of the price of injection or blow moulding tools, so new products can be brought to market comparatively cheaply and quickly.

Flexible process: Rotational moulding can be run for one-off products if necessary, making the process ideal for small to medium sized batch runs. Injection moulders generally require runs of several hundred products for the process to be cost-effective.

Wall thickness: Roto moulded products offer a uniform wall thickness of between three and five mm, and in some cases up to eight to nine mm, depending on the application.

Surface texture: Different surface textures can be easily achieved on any product by applying a shoot peen (rough textured) finish that is masked off to leave certain areas of the tool smooth.

Range of applications: The practical use of roto moulded products is wide-ranging, from garden and street furniture to tractor parts, kayaks and equestrian products.

Grades of material: Excelsior offers a choice of different grades of material including anti-bacterial material for use in the food and hygiene sectors. It also offers a cost-effective black recycled material made from its off-cuts.

The rotational moulding process is elegantly simple.

Polyethylene powder is placed into a mould which is clamped shut and moved into an oven chamber. The tool is heated up to between 220°C and 400°C while rotating on two axes. As the tool heats up, the powder melts and adheres to the inside of the mould.

Once the plastic is completely fused to the surface, the mould is withdrawn from the oven and cooled. The plastic product is then removed from the mould and allowed to cool further. For products of a technical nature, Excelsior normally uses a wooden cooling jig at this stage as it helps ensure the product doesn’t shrink too much and assists with maintaining critical features.

Excelsior operates a mixture of rotational moulding machines, selected according to the complexity of the end product. These range from multi-arm computer programmed carousel and clam shell machines to tried and trusted open flame rock and roll machines.

Excelsior is more than just a manufacturer of roto-moulded products:  it manages custom contracts from concept all the way through to production.

Boasting its own in-house Computer-Aided Design (CAD) facility, rare within the roto-moulding industry, the company is able to help customers to design their products.  Because the CAD facility is in-house, the design process is extremely efficient, and this helps to keep costs down and to reduce lead times.

Unlike many of its competitors, the company also has its own in-house sheet steel tooling facility.  This means that not only can the company create bespoke tools for individual jobs, generating output that meets precisely the customer’s initial requirement, but it can do so quickly, efficiently and cost-effectively.

Where elements of contract jobs require outsourcing, Excelsior does so with discernment, and has over the last 40 years developed close associations with a select number of trusted suppliers.

For example, it may be necessary to consider cast aluminum or computer numerical control (CNC) instead of sheet steel tooling in order to achieve a higher level of detail and surface finish. In these instances, the company works with market-leading tooling companies in the UK and Europe who manufacture tooling of an extremely high standard at an affordable price and who are used to working within strict deadlines. Excelsior oversees projects from start to finish and is more than happy to visit toolmakers in Europe with customers to ensure that every stage of the project runs smoothly.

Excelsior also works closely with three dimensional (3D) printers who can make a three-dimensional solid object of virtually any shape from a digital model using CAD software. Using an additive process, where successive layers of material are laid down in different shapes, a product can be printed in sections and built, enabling the customer to see exactly what the finished article will look like before it invests in expensive tooling.

Innovative outdoor company Adventure Orb Designs Ltd, is just one of Excelsior’s satisfied custom contract clients.

Adventure Orb approached Excelsior to help design and to manufacture a robust luggage item created for use in the harshest conditions.

Excelsior supported Adventure Orb with the product’s design, and manufactured the main body of the aptly-named, easily manoeuvrable, waterproof, corrosion resistant and shatterproof Tough Box (TBX).

Unique in its combination of features, one of the TBX’s greatest assets is the single piece composition of its roto-moulded polyethylene main body, which, in the absence of joins, is waterproof and able to float.

Adventure Orb awarded the deal to Excelsior because it required a firm that could contribute to the design of the product as well as undertake its manufacture.  Excelsior is one of the few companies in the roto-moulding sector with an in-house CAD design facility.  It was able to work with the customer to develop its initial concept into a valid design, and then translate the design into a 3-D model.  The first batch of TBXs was completed in spring this year.

Said Adventure Orb’s managing director, ex-serviceman Ben Sherwood:  “Another of Excelsior’s main advantages was its attitude:  it shared my passion for innovation, and the team was never short of ideas.

“Its 40 year roto moulding heritage and family ownership was also immediately apparent, not only in the skill that the firm brought to the job, but also in its pride and passion.”

So, whether you want to lock it, trek with it or even play on it… no matter what you want to use plastic for, why not break the mould and choose Excelsior as your extraordinary roto moulding partner?

Excelsior has the bright people, clever moulding expertise and extensive design knowledge needed to bring even the most unusual plastic projects to life. From the simple to the seriously complex, if you are looking for quick project timescales, an extremely high level of finish and very competitive pricing, get in touch.