Lubricant guide ·
Choosing hydraulic oil for injection moulding machines
Grade, zinc or zinc-free anti-wear oil, oxidation stability, keeping servo valves clean and when to change the oil, with the anti-wear oils we stock.
Plastic moulding units in Metoda GIDC, Shapar-Veraval and around Rajkot run their injection moulding machines for long hours, often around the clock. The hydraulic oil works hard. It is pumped at high pressure, runs warm, and passes through fine proportional or servo valves thousands of times a shift. Choosing the right oil, and keeping it in good condition, protects the pump and valves and keeps cycle times steady.
Grade: usually ISO VG 46 or 68
Most injection moulding machines call for an anti-wear hydraulic oil in ISO VG 46 or ISO VG 68, and the machine manual or the label on the oil tank says which. Older machines, and machines in hot sheds, are more often on VG 68. Many newer machines with servo-driven pumps and tighter temperature control use VG 46. Follow the machine builder's specification. If the manual is lost, tell us the make and model. Our guide to choosing between ISO VG 32, 46 and 68 explains what the numbers mean.
Anti-wear type: zinc or zinc-free
Anti-wear hydraulic oils (HLP to DIN 51524 Part 2, often sold as "AW") protect the pump under pressure. Most use a zinc-based anti-wear additive, which works well in vane and gear pumps. Some machine and pump makers specify a zinc-free (ashless) oil instead, for example where components are sensitive to zinc additives or where long oil life and filterability are priorities. If your manual says zinc-free, stick to it.
Oxidation stability and filterability
The oil runs warm for long hours, so oxidation stability matters. An oil that oxidises quickly darkens, thickens and leaves varnish on valve spools, which leads to sticking valves and erratic cycles. Filterability matters too, because the oil passes through fine filters all the time. Both are shown on the product data sheet, so compare those figures, not just the grade.
Keep it clean
Proportional and servo valves have very fine clearances, and dirt is their biggest enemy. Change filters on schedule, and whenever the clogging indicator shows. Fit and maintain a breather filter on the tank. Top up only from clean, closed containers, using a clean funnel or a filter trolley, and never leave the tank open.
Fresh oil from a drum is not always clean enough for servo systems, so filtering it on the way in is good practice.
Watch the temperature
Keep the oil cooler working. Scale builds up in water-cooled coolers where the cooling water is hard, and a choked cooler lets the oil run hot. Hot oil oxidises faster and can thin out below the pump's working range. Keep the tank temperature within the range the machine maker gives, and treat a rising oil temperature as a warning, not a normal summer condition.
When to change the oil
Change by condition or on the maker's interval. Oil analysis tells you when the oil is really worn and catches problems early. The useful checks are viscosity, acidity, water content and particle count. Without analysis, follow the machine builder's interval, and change sooner if the oil darkens sharply, smells burnt, foams or turns milky.
Anti-wear hydraulic oils we stock
These are anti-wear hydraulic oils we stock in the grades injection moulding machines commonly use. Oils in the same column share the ISO VG grade and anti-wear type, but confirm the full specification on the data sheet against your machine manual before changing oil. We are a multi-brand retailer, not an authorised dealer of any of these brands.
Buying hydraulic oil for moulding machines
Our shop is at Tilara Gate, near the Shapar Veraval Industrial Association. Regular customers in Shapar-Veraval get same-day delivery (a minimum order applies). We also deliver to units in Metoda GIDC, also known as GIDC Lodhika, and across Rajkot, with timing confirmed per order. Every order comes with a GST bill, and factories get a bulk discount. See all the hydraulic oils we stock.
