A Guide to Selection of Suitable Oil for Broaching

Broaching is a machining process that removes material consistently and accurately with a toothed tool. It is an intense metal cutting operation performed on a rounded, flat or contoured substrate. The specialised multi-toothed tools used during the broaching process are aligned to remove metal progressively as it passes through the substrate. The process is similar to threading a car’s spark plug, except one uses a fluted broaching tool and cutting oil instead of spark plug wire and oil-based lubricant. Broaching presents several advantages over threading and tapping methods and provides an overall improvement in manufacturing quality. There are 4 types of broaching machines: 

• Horizontal broaching machine 
• Vertical broaching machine  
• Surface broaching machine
• Continuous broaching machine

Broaching oil has a significant impact on the broaching process. The type of broaching oil impacts the productivity and the lifetime of the broaching machine tool. This is why choosing the right cutting oil for broaching is essential. This blog covers the factors to be considered while choosing a broaching oil. 

1) Criteria for effective cutting oil 

The selection of effective cutting oil is the key to successful broaching. When the right cutting oil is selected, it will provide a smooth surface, reduce friction, and allow the metal to be removed with high quality. Furthermore, the oil must have a low viscosity, low volatility, a low flash point, and high shear stability.

The following criteria must be considered when selecting an effective cutting oil:

• Viscosity – The oil’s viscosity indicates its flow properties, allowing you to achieve better results during broaching. The downside is that this can lead to a longer processing time.

•  Flash Point – The flash point of the cutting oil should be below 60°C. This reduces potential workplace hazards like fires or explosions due to friction caused by overheating the workpiece during broaching.

•  Shear Stability – Shear stability refers to how quickly an oil breaks down during heating and cooling cycles and can influence the cooling time between broaches or other heat treatment processes such as quenching or tempering.

2) Selection of the perfect coolant 

The selection of the perfect cooling during the brooching process completely depends on the chemical composition of the metals involved in the broaching process. The cutting fluid must be adjusted according to the type of metal. The first step to choosing the right coolant is determining what type of metal you will be broaching. You should use a water-based coolant when broaching mild steel. An oil-based coolant will be needed if an iron alloy or stainless steel needs to be broached.

Next, determine how many operations will be required to complete the machining process. It will allow you to determine how much material your machine can handle without overheating.

Conclusion: 

Choosing the right cutting fluid is crucial to improving your broaching machining procedure. The right cutting fluid reduces operating costs and increases profitability. Choosing a high-performance cutting oil from a reputed manufacturer is equally important as their broaching oils are formulated after thoroughly analysing industry requirements. 

Castrol is the global leader in liquid engineering. We provide a comprehensive range of cutting oils for all industrial sectors that address every requirement. Our cutting fluids are proven to improve manufacturing and prolong machine life.