Specialist seals for best selling recycling tool

Apex Hydraulics were recently requested to manufacture a number of bespoke cylinders for a business specialising in the production of recycling plant equipment. The company uses cutting edge technology to remain at the top of their sector, providing market leading recycling tools and machinery.

One such tool is a machine that squeezes recyclable materials into tight bales, ready for economical transport and processing.

It involves a hopper, feeding the material (for example, cardboard) into a channel. The four-metre-long hydraulic cylinder pulls back a sliding head, attached to the baler, allowing the hopper to drop the card into the baling machine, then the cylinder takes it into the end compression chamber. The cylinder therefore needs to provide a huge amount of force, which is dual acting, providing both the forward and backwards motion hydraulically.

The challenge

The commission had a challenging element to it, due to the variable hydraulic pressure throughout the stroke. There is an initial extension of the cylinder, as the cylinder ram makes its way up to where the cardboard has entered the hopper (no pressure). Then it forces the card from the hopper into the compacting chamber (some pressure) before reaching full compression and baling it within the compression chamber (extreme pressure).

Once the bale has been made, the cylinder needs to retract quickly. Speed is a vital aspect in these machines. When competing for sales, a machine that can work more quickly will always have an edge over slower competitions. Therefore, the more swiftly the machine can go from open to closed and back, the more the machine can process within the same amount of time. This piece of equipment advances in 6 seconds and (due to the lower volume of oil) retracts in 4, whilst in production mode.

These machines may be used constantly for up to 12 hours a day. The high cycles mean that this machine requires an extreme durability to cope with the wear and tear, which tends to be the cause of failure for most machines of this type.

Previously to approaching Apex, the company had experienced problems with the base end failing at the weld.

In addition to the requirements of durability and quality, the company also required a very swift turnaround on this product, in order to be able to fulfil new orders for the product quickly as they came in. The tool is now a top seller within the sector, as their name is increasingly well known for quality.

Apex solutions

To solve the issues caused by the extreme repetitive movements of the fabrication and the potential burn-out of the machine, Apex provided a bespoke durable seal kit. To avoid machine marks and grooves, the seals are all injection moulded. There are several seals in a configuration, with a combination of low- and high-pressure seals put into a specifically designed order. Seals that are very good at high pressure often have some leakage at low pressure. The seal behind it then catches any low-pressure oil that has been allowed to pass. This allows any contaminants to be removed before the main seal, meaning the main seal will last for longer.

Apex designed trunnions for the mounting. As the slide box may have subtle amounts of motion within the course of the cylinder stroke, trunnions allow the cylinder the flexibility of movement to be able to follow.

In response to the previous weld failures, Apex utilised full penetration welds to prevent weld fatigue failures.

To respond to the short lead time required by the company, Apex Hydraulics keeps the necessary raw materials and some small components in stock, as well as having the design measurements on file, meaning that they can weld, assemble, test and paint with a very fast turnaround time when required. It also means that they can be produced at a more cost-effective rate than if a bespoke cylinder had to be produced each time it was ordered.


The result is a bespoke cylinder, that can be manufactured at very short notice. The welds are more durable than as produced by previous manufacturers, with premium seals, guaranteeing a longevity in keeping with the company’s top reputation.

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