What does Metal-Stamping Equipment Lubrication do?
High-performance lubricants protect gears and bearings from micropitting, and hydraulic systems from varnish. They can also reduce operating temperatures and the electricity needed to operate the stamping equipment. There are various lubricants used in metal-stamping equipment.
Types of Metal-Stamping Equipment Lubrication Systems
Hydraulic Oil. Hydraulic oil is an important part of metal-stamping manufacturing operations. There can be two hydraulic systems in a metal-stamping press, the die cushion and the crown system which may include a clutch. Proper die-cushion operation is critical to part quality and protects the die from damage. The clutch system is a critical safety system of the press, protects the press from damage and contributes to the final part quality. Both the die cushion and the crown hydraulic system and clutch are fundamentally hydraulic systems. Because hydraulic systems do not prefer friction, whereas clutches require “controlled” friction, the chemistry of a hydraulic oil for a cushion is different from the chemistry of a hydraulic oil for a clutch. You’ll achieve maximum reliability by using lubricants specifically designed for each application. The common denominator for both systems is excessive heat. Heat thins oil, and it causes excessive wear, oxidation, varnish and deposits on machine components like servo valves, pumps and clutch plates, leading to short oil and equipment life and downtime. Typical anti-wear hydraulic oils fall short in protecting high-stress systems. Metal-stamping presses require high-performance, high-viscosity-index hydraulic oils that resist varnish, while inhibiting rust and oxidation and must also contain anti-wear additives.
Gear Oil. Industrial gear oils help protect against wear in normal gearboxes, but there is nothing normal about large industrial gearboxes found in the metal-stamping industry. Micropitting wear can be a problem in some metal-stamping presses. This fatigue wear can only be solved with a high-performance gear oil. Only top-tier, high-performance gear oil can provide improved fluid-film thickness and friction reduction to reduce or eliminate micropitting.
How to Choose the Correct Lubricants for Your System
Consideration 1 – OEM Equipment Specifications.
Each piece of machinery should have a user or service manual that recommends a list of qualified products and provides general specifications regarding cleanliness and viscosity. However, it may not consider the average operating temperatures of the equipment, which can greatly affect the longevity of the oil. A service manual may not always be available, so it is important to understand what your equipment requires based on your own operating environment.
There are many considerations for selecting the appropriate lubricant. To make the appropriate selection, one should always consider the Application, oil viscosity, additives and base-oil types.
Most OEM oil recommendations specify the minimum, which is mineral oil. Many OEMs still think of oil as a commodity and not a component of the lubrication system. A low-cost mineral oil must be changed often, while varnish formation can make that low-cost lubricant cost hundreds of thousands of dollars more in the long run.
Consideration 2 – Viscosity. Viscosity, defined as a fluid’s resistance to flow, is one of the most important characteristics of a lubricant. How viscosity reacts to external factors such as temperature, pressure and speed determines how well your equipment components will be protected. When deciding what type of oil your press requires, make sure you choose an oil with a viscosity rating that is optimal for the external factors in which your equipment will be operating.
Consideration 3 – Additives. Oil additives are substances that are added to base oil to improve its performance in specific operating environments. Various types of additives can be used in industrial lubricants, including rust and oxidation (R&O) inhibitors, anti-wear (AW) agents, extreme pressure (EP) additives, anti-foaming agents and more. In addition to the functions they perform, additives are chosen for how compatible they are with the base oil and its current compounds.
Consideration 4 – Base Oil. Industrial base oils can be made from mineral or synthetic oils. Mineral oils (another name for mineral oil is petroleum oil) come from crude oil and are highly dependent upon their refining process for quality, whereas synthetic oils are man-made oils that are manufactured by chemically breaking down and rebuilding petroleum molecules. This allows synthetic oils to be formulated for specific applications.
The American Petroleum Institute (API) has designated five groups for base oils.
Group I base oils contain less than 90% saturates and have a viscosity index range of 80 – 120. They contain > 0.03% sulfur and they are manufactured through solvent refining and are the cheapest oils on the market.
Group II base oils contain more than 90% saturates and have a viscosity index range of 80 – 120. They are manufactured through hydrotreating and contain < 0.03% sulfur. They are a step up in quality from Group I base oils due to the extra hydrotreating process.
Group III base oils are greater than 90% saturates and have a viscosity index higher than 120. They are manufactured through hydrocracking and are reconstructed molecules that offer improved performance over Group I & II base oils.
Group IV base oils, also known as polyalphaolefins (PAOs). They are chemically engineered synthesized base oils. PAOs offer excellent stability, molecular uniformity and improved performance. Because of their uniform molecule structure they have less internal friction which relates to higher operating efficiency.
Group V base oils include all base oils that do not fall into Groups I-IV. Because they can be low-quality bean oils or high-quality esters, Group V oils are not necessarily better than Group I-IV oils.
When choosing which base oil is appropriate for your application, consider the temperature range and operating conditions of the application in which it will be used.
Consideration 5 – ISO Cleanliness Requirements. The International Organization for Standardization (ISO) developed a cleanliness code used to analyze lubricants, helping determine the number of particles per milliliter in three size ranges.
Particles ≥ 4 micron
Particles ≥ 6 micron
Particles ≥ 14 micron
Expressed as xx/xx/xx
An OEM or user will typically establish a cleanliness goal for the fluids used in equipment. This is important to consider when selecting lubricants for manufacturing operations because low ISO cleanliness values can cause reduce wear and can assist in increasing drain intervals.
Some examples of general cleanliness-code targets:
Gear pumps/motors 19/17/14
High-pressure pumps/motors 18/16/13
Industrial servo valves 16/14/11
Together, your system manufacturer and a certified lubrication specialist should be able to review your manufacturing process and make an appropriate recommendation.
Still have questions? Visit our Metal Stamping page to learn more.