Hydraulic systems

ARBURG – Your competent partner for efficient injection moulding

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Plastic is booming! 

A total of 348 million tons of plastic products were produced worldwide in 2017; that‘s a 3.8 percent increase on the previous year. And these products include far more than just plastic packaging. Among other things, plastics are also used to manufacture components for the automotive industry, electronic communication and entertainment devices, and medical equipment. When it comes to getting more out of plastics, the German mechanical engineering company ARBURG has the ideal solutions. 

One of the world‘s leading manufacturers of machines for processing plastics, ARBURG is also a pioneer in its sector, driving development in key areas such as production efficiency, Industry 4.0, and digitalization.

The company‘s product range encompasses hydraulic, hybrid, and electric ALLROUNDER injection moulding machines with clamping forces between 125 and 6,500 kN, while the Freeformer additive manufacturing system, together with robotic systems, client and sector-specific turnkey solutions and other peripherals, rounds out ARBURG‘s wide variety of modular machines. 

ARBURG puts manufacturing efficiency at the heart of everything it does, and does so with the entire value chain in mind. Its objective is to ensure that ARBURG‘s clients can manufacture their plastic products to the highest quality standards and at minimal unit costs, from individual parts to large-volume production.

Whatever the injection moulding task at hand, ARBURG has just the technology and the processes that their customer needs - in modular form and individually tailored. Its machines are manufactured exclusively at ARBURG‘s German main plant in Loßburg, Baden-Württemberg,  where a first-class customer support experience is also provided on-site by ARBURG‘s global sales and service network. 

Hydraulic oils to meet the highest requirements

Hydraulic, hybrid, and electric ALL-ROUNDER injection moulding machines require high-quality hydraulic oils. In the case of smaller machines, the quantity of oil used is generally between 40 and 80 litres, whereas mid-sized machines can use as many as 320 litres. The large hydraulic and hybrid ALLROUNDERS use between 400 and 800 litres of oil. In addition to lubricating, cooling and protecting pumps and moving components, the main task of hydraulic oils is power transfer, including provision of dynamic injection and retention forces. The clamping force spectrum of ARBURG injection moulding machines ranges from 125 to 6,500 kN.

For the ALLROUNDER models, HLP 46 fluids are the most commonly used, although HVLP 32 fluids are also used in individual cases. The majority of these are highly refined, mineral-oil based hydraulic oils with zinciferous additives, which give the oils EP characteristics. Partly or completely synthetic HVLP hydraulic oils or zinc-free fluids are also increasingly being used, however. Meanwhile in the food and pharmaceutical industries, physiologically harmless hydraulic oils with NSF-H1 registration or with kosher or halal certification are often used. 

ARBURG specifies hydraulic oils with the following characteristics: 

  • Very good lubricity and high shear stability
  • Outstanding EP and anti-wear protection and good ageing characteristics 
  • Very good air release time and minimal foam formation tendency
  • Excellent demulsifying capacity and water separation
  • High thermal resistance with low oxidation tendency
  • Extremely good seal compatibility
  • Good filterability, including a 1 µm filtration system
  • Partially synthetic or synthetic fluids with a high viscosity index, and mineral oil-based HVLP oils without long-chain VI improvers
  • Available worldwide, and always with the same level of performance. 

Whatever the country in which a mineral oil company produces its lubricants, the fluids used in ARBURG injection moulding machines must always be of a consistent quality. The same requirement is posed by many internationally active machine manufacturers. When it comes to selecting base oils, this factor has an enormous impact. Until the turn of the millennium, hydraulic oils were manufactured predominantly from class I and II paraffin-based base oils. Today, increasing use is made of class III hydrocrack oils, as well as class IV synthetic oils based on poly-alpha olefin (PAO). These base oils can be produced worldwide with identical characteristics, although often only with difficulty. They give the hydraulic oils not only better oxidation stability, but also and most importantly a significantly higher viscosity index, so the viscosity of the oils is less sensitive to temperature.

In order to produce an HVLP oil with multigrade features from a mineral oil-based monograde HLP oil, special VI improvers must be added to the base oil. These consist mostly of long-chain hydrocarbon molecules, which contract at low temperatures and stretch at high ones. These are not shear-stable beyond a duration of use of over 10,000 operating hours, however, so their positive effect on the viscosity of the HVLP oils diminishes over the duration of use. This is why ARBURG specifies the use of mineral oil-based hydraulic fluids that do not contain any shear-sensitive VI improvers. 

Oil analyses are a part of maintenance

For the operators of ARBURG injection moulding machines, OELCHECK lubricant analyses are an important part of monitoring oils and systems. An annual oil analysis is an integral component of the ALLROUNDER maintenance schedule. For even better monitoring, ARBURG recommends regular trend analyses at intervals of six months. This allows contamination and oxidation trends, as well as possible component failures, to be identified at an early stage. In the event that sources of errors are discovered, machine availability can be increased with preventative maintenance. In the case of large and heavily utilised machines, many operators use synthetic-based hydraulic fluids in addition to running trend analyses for condition-based oil changes. Based on OELCHECK lab reports and in consultation with ARBURG, oil change intervals of 20,000 operating hours can in many cases be extended, thereby significantly reducing expenditure on costly synthetic oils. 

Analysis kits are always to hand

Most oil samples are taken by the plant operators. In order to be able to react quickly on-site and take oil samples at short notice, however, every ARBURG service engineer always has their own OELCHECK all-inclusive analysis kits to hand. If, for example, filters need to be changed unusually often, the oil shows increased foam formation, or there are doubts about the type of oil used or its quality, then these analyses can provide useful information. They help service engineers to quickly determine the causes and take appropriate action without delay.

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