In stamping operations, improper or inadequate lubrication can bring even the mightiest of presses to a standstill. But choosing the right lubricant isn’t always straightforward. For instance, what works well for high-strength steel in a progressive die line might cause galling or leave unwanted residue on softer materials such as aluminum or copper alloys.
This explains why stamping houses must consider a whole host of factors when selecting the correct lubricant. These include workpiece material, tooling type, application method, downstream operations and more, all of which can have costly repercussions on throughput and part quality.
To help manufacturers navigate this complexity, Stamping Productivity spoke with Marvin Redetzky, an application engineering manager with Perrysburg, Ohio-based Master Fluid Solutions. Based in Düsseldorf, Germany, Redetzky supports customers across Europe and brings deep expertise in the tribological challenges of metal forming. Whether talking about environmental regulations or operator health, he offers important advice for stamping professionals looking to optimize their metalworking fluid use and product selection.
In this Q&A, Redetzky explores both the technical and practical aspects of stamping lubrication and gives clear guidance for manufacturers looking to strike the right balance between performance, cost and sustainability.
STP: How do different lubricant chemistries interact with the high-performance tooling materials used in stamping dies?
Redetzky: Coatings and high-performance tooling materials have the potential to greatly enhance the tribological properties of mechanical systems. These materials are generally more resistant to wear, but also more inert to lubricants.
Similarly, how does the workpiece material influence the choice of lubricant?
Different materials mean different material compatibilities. Especially with aluminum alloys or yellow metals, the right selection of additives is crucial to prevent staining. This is because soft and gummy materials require more lubrication, such as esters, while hard materials, such as stainless steel or nickel-based alloys, require additives, such as extreme-pressure additives like phosphor and sulfur, to prevent the welding of the tool and workpiece at high pressures. And for steel parts, good corrosion protection is essential for intermediate storage.
What application methods are best suited for different part geometries or production speeds?
Rollers are good for sheet material and generate a uniform film on the metal surface. The right setup is important to prevent a too-thin or too-thick film that can negatively affect tool life, the stamping operation and subsequent operations, such as part cleaning.
At higher production speeds or for more complex part geometries, a spray/misting system that also offers a cooling effect for the tool can be more convenient. Due to the targeted lubricant distribution, this system can also reduce overall consumption and increase tool life and cleanability of the stamped parts. However, compressed air and extraction systems are often necessary to safely operate spray/misting systems, and not all lubricants, such as those with a high viscosity, can be sprayed.
What lubricant properties help prevent residue buildup on press components and other equipment?
Native esters, in particular, tend to oxidize at higher temperatures, which can lead to residues that are difficult to remove. Solvent-based products with a low viscosity, on the other hand, enable residue-free manufacturing.
What performance metrics should buyers evaluate when comparing lubricants?
Tool life and part quality are affected by film strength and other lubricant properties. Evaporation rates and residue-free parts after an annealing process can also be important criteria for subsequent operations. However, it’s generally easier for customers to measure the number of stamped parts per tool than to analyze these properties.
How can the right lubricant extend tool life?
The main tasks of the lubricant are to reduce friction and wear and to remove heat and small particles from the contact zone between the tool and the workpiece. All of these factors directly affect tool life and help to achieve a good surface finish in stamping operations.
What are the health and safety considerations when selecting lubricants, particularly in terms of volatile organic compounds (VOCs), misting or skin contact?
All lubricants are chemical products. Even if they are designed to be skin
and environmentally friendly, contact should be kept to a minimum as they can still dry out the skin. When using spray/misting systems or products with a high VOC content, manufacturers should use an extraction system to prevent the inhalation of small particles.
How do lubricants impact downstream operations like welding and painting?
The more residue on the parts, the more likely that subsequent operations will be affected. Because of this, the right application system can help to avoid problems in downstream operations. Different kinds of lubricants, such as esters or mineral oil-based, and the additive selection can affect the cleaning and other subsequent operations. Note that it’s important to test cleanability and compatibility with subsequent operations before changing a lubricant.
What role do environmentally friendly lubricants play in modern stamping operations?
Bio-based lubricants are more favorable from an environmental or sustainability perspective. Their high lubricity also often means higher performance. Nevertheless, bio-based lubricants are prone to oxidation, which increases the residues on surfaces and makes their cleanability more difficult. This is why water-soluble synthetics, such as those based on synthetic esters, might be a good compromise between performance, fast cooling effect and clean surfaces.
It must be considered that the preparation of these fluids requires more effort than using neat-type products [concentrates must be diluted with water].
How do upfront lubricant costs compare to the long-term savings through reduced scrap, tool wear and maintenance?
A more expensive lubricant can be much cheaper than a low-cost product when comparing the total costs of ownership. The reasons can be varied but include increased tool life [meaning more stamped parts per tool], better cleanability, fewer residues, less rework and a lowered scrap rate, lower consumption [saving money on waste disposal], and, most importantly, a lower risk of skin and health problems for the people on the production floor.
