Minimum Quantity Lubrication (MQL)

In the metal industry, machining processes take place in a number of contexts. Whether in the industrial sector, in the skilled trades or in high-tech manufacturing processes – to ensure an optimal workflow, they require the appropriate process. Depending on the tool, the machine tool and the workpiece, machining is performed as dry or wet machining, for example within the framework of CNC technology.

Minimum quantity lubrication (MQL), also referred to as minimum quantity cooling lubrication (MQCL) or near-dry machining, is a significant advancement from wet machining. It is based on the idea of preventing the frictional heat that is generated during the machining process. Without cooling, the machine and workpiece would sometimes overheat considerably and suffer damage.

Previous wet machining methods use flood coolants, i.e., they involve the workpiece being literally flooded with coolant. This has various disadvantages, but until recently this was the only available option. With sophisticated dosing technology from WERUCON, you can make sure that machining processes are carried out at a completely new and modern level by using minimum quantity lubrication.

What happens during minimum quantity lubrication (MQL)?

MQL is fundamentally different from wet machining: it is using lubricants instead of coolants. With this method, the cooling lubricant is an air-oil mixture and is applied precisely at the working point. This allows it to perform its cooling capacity during the machining process. In contrast to flooding, considerably less lubricant is needed. There are four challenges associated with this process: Firstly, the cooling lubricant must be accurately dosed. With our products, we guarantee process-reliable dosing. Secondly, the cooling lubricant must be fed to the tool in a precise manner.

This is achieved by using special nozzles from our range. Thirdly, it is important that the chip removal is successful, and lastly, the escape of aerosol vapours from the machines must be prevented. In order to ensure all this, the tool and machining systems have to be retrofitted.

While you can easily convert circular and band saws, the modernisation of other machines, such as those using CNC technology, is more extensive and therefore more cost-intensive. However, the advantages of the change clearly outweigh the disadvantages. We will discuss these separately after we have had a closer look at the technology in the next section.

 

Selected fields of application for MQL:

• (Deep) drilling, turning and milling
• Thread cutting / thread forming
• Deformation processes
• Applications with various saws, gear cutting machines and rollers

 

Different minimum quantity lubrication (MQL) systems

While standard lathes and saws can easily be retrofitted with MQL, high-performance cutting systems require more extensive modifications. MQL can be found in two different versions: those with internal and external feed. 

MQL systems with internal feed use a machining spindle that supplies the lubricant directly to the tool or toolholder. This allows for an optimum lubrication of all relevant surfaces, while at the same time maintaining precise control so that not too much lubricant is applied.

Internal feed MQL systems are further divided into two types: the one-channel or external mixing system and the two-channel or internal mixing system. The main distinction is that in one-channel systems, the aerosol is mixed outside the spindle, whereas in two-channel systems, the mixing occurs inside the spindle.

In the context of the external feed, a nozzle mounted on the machine tool plays the decisive role. It delivers the minimum amount of lubricant directly to the point of use during machining.

The advantages of minimum quantity lubrication (MQL) using WERUCON dosing technology

By using our dosing technology products for minimum quantity lubrication, you profit from multiple advantages for your company. The most obvious benefits of MQL are financial. Furthermore, you will observe an improvement in the fields of occupational health, work safety and environmental protection with MQL.

Work safety

In environments with high humidity due to lubricant escape, the risk of slipping increases and so does the risk of occupational accidents. By providing a dry environment around machinery and workplaces, you ensure increased occupational safety thanks to MQL.

Occupational health

With minimum quantity lubrication, the lubricant is almost completely used, and any escaping vapours are greatly minimised. This reduces the number of cooling lubricant-related illnesses, for example of the skin or respiratory tract.

Environmental aspects

For the same reason, the impact on the environment also decreases, as the lubricants are only emitted to the required extent. Environmentally harmful gases and emulsions decrease, and the risk of accidents is further reduced.

Financial aspects

By far, the most significant impact of the use of MQL systems and products is on finances. Cost reductions result from the elimination of disposal technology and supply technology for cutting fluids.

Furthermore, it also eliminates the resources for testing the cutting fluid. This results in planning advantages, particularly with regard to the disposal of cooling lubricants, but also their purchase, storage and transport. Depending on the duration of and the type of process, a 25 % or more reduction of coolant can be achieved.

In conventional wet machining with flooding, it is absolutely essential to clean the workpieces after completion, which is often a time-consuming process. Washing and other processes do not only cost time, but also money, and MQL allows them to be omitted completely or reduced to a minimum.

In this context, the concept of recycling is crucial: Machining processes always leave residues and chips. If these are contaminated by oil lubricants and other substances, they constitute hazardous waste and must be disposed of properly, at high cost. The dry chips after modern MQL, on the other hand, are valuable recycling material that can be resold or reprocessed.

Do you have any questions about our products or minimum quantity lubrication and its possibilities? We look forward to hearing from you!