Metal Stamping Lubrication 101
Lubrication is arguably one of the most important aspects of the metal stamping process. Without proper lubrication, any metal forming process will quickly succumb to excessive wear leading to galling, scoring, and cracking of parts. This leads to increased scrap, premature tooling wear, and, as any metal stamper knows, decreased profit.
Here we've created a helpful guide to talk through all of the basics of metal stamping lubrication, the application methods available, and why an investment in an advanced stock lubrication system should be a critical part of any metal forming strategy.
We'll also cover how to choose the right lubrication application system for your facility and everything to consider before your purchase.
What is Metal Stamping Lubrication?
Metal Stamping is a manufacturing process in which metal in the form of a flat sheet is converted into two or three dimensional shapes or parts. Both the metal to be formed and the tooling which acts upon it contain microscopic peaks or asperities which create large amounts of friction as these two surfaces are in sliding contact. Metal Stamping Lubrication refers to the addition of a lubricating film which protects each surface from the other's asperities.
Why is Lubricant Used in Metal Stamping?
Lubricants in the metal stamping process serve the primary purpose of reducing friction through lubricity. This in turn protects expensive tooling and reduces the likelihood of metal forming irregularities such as galling, scoring, welding, etc. A lack of lubrication or improper application of lubricant can quickly result in poorly formed parts and thousands of dollars in damage to costly tooling. Overall, metal stampers use lubricant to ensure their tooling produces a maximum quantity of parts with a minimum quantity of maintenance costs and interruption of the process.
Precise Lubricant Application
Precise application of stamping lubricants is necessary for the metal stamping process to remain repeatable. Lubricants cannot deliver any benefit if they do not adequately and consistently reach all critical areas of the die/tooling. Not only should a lubrication system ensure that all important areas of the tooling receive lubricant, it should ensure that a proper and repeatable amount of lubricant is delivered. A precise lubricant application method will allow for fine tuning of the lubricant quantity applied and will deliver that quantity accurately from the first part stamped to the millionth. Careful consideration of lubrication application methods in relation to specific stamping processes and to the lubricants used is a must.
Imprecise Lubricant Application
Since precise application of stamping lubricants has a positive effect on the metal stamping process, it follows that imprecise application has negative effects. Lubrication application methods which provide spotty lubrication or create any type of 'lubrication void' cannot be trusted to protect all critical die areas. Lubrication methods which overapply lubricant or apply it where it is not needed are detrimental as well. They result in not only wasted lubricant, but can produce hazardous and unsightly conditions such as messy floors and equipment. Overapplication of lubricants can also result in customer rejection of wet stamped parts and/or extra or increased part cleaning costs.
Why Lubricant Should be a Before-Thought, Not an Afterthought
One of the major reasons why the problems we've mentioned earlier occur is that most treat metal stamping lubrication as an afterthought, rather than thinking about it when purchasing tooling and equipment. Lubrication should be a part of any metal stamping strategy as it will help determine the quality and consistency of the products being created, as well as the overall life expectancy of the tooling.
It is not an exaggeration to say we've seen businesses who use 50% less lubricant by using a more precise application process than they previously were. These businesses not only enjoy savings on lubricant but also housekeeping savings by eliminating the mess caused by excess fluid. When fluid mess and hassle is eliminated, you'll have a cleaner, safer facility leading to higher employee satisfaction and greater efficiency!
If all of these things had been considered upfront during the buying process, the metal stamping facility could have enjoyed the savings at the outset instead of treating lubrication as a minor add-on at the end of a project.
When considering metal forming lubrication upfront, be sure to properly test the lubricant in a similar environment that the tool will operate in. Many times when testing lubricant, it is tested by hand and thus does not recreate the actual environment of the tool being used repeatedly on a daily basis. So be sure to ask questions and find ways to test lubricants in similar environments to what your tool will be operating under.
Stamping Lubrication Application Methods
The two main types of lubrication application methods are contact and non-contact. There are benefits to both and many times the choice of which one to choose comes down to the application and the type of part you want to create.
Non-Contact Spray vs Contact Lubrication
Contact lubrication methods include applicators that roll coat, wipe, or submerge and squeegee the material. Contact applicators can provide the neatest application and provide consistent coatings over the entirety of the part material, top and bottom.
For contact lubrication, a roll-on application is ideal. Rollers give you the cleanest, most consistent application. For some extremely thin materials, a wiping style applicator such as our thin stock lubrication system is more appropriate.
Contact Pros and Cons
Pros – neatest, most consistent application for the money
Cons – touches the material, can only be used on smooth/flat materials
Noncontact lubrication generally refers to an application by means of a spray. Spray applicators can use airless spray, air-assisted spray, or electrostatic spray nozzles. Each of these has its place, but the main benefit of noncontact lubrication is that nothing but the fluid physically touches the material. Noncontact lubrication does sometimes require an overspray management system.
Non-Contact Pros and Cons
Pros – inexpensive and easy to implement
Cons – overspray mess, expensive to monitor, can be inconsistent
How to Choose the Right Metal Stamping Lubrication System
There are several important considerations when selecting a lubrication system for metal stamping. A good system manufacturer will take the time to discuss and understand your process and will recommend a tailor-made system to fit your needs. While not comprehensive, the following questions should help you when evaluating a potential lubrication system:
How fast is your press running?
To precisely dispense a metered amount of lubricant, a lubrication system must be able to keep pace with your press rate (strokes per minute), material feed rate, and potentially, conveyor speed. A lubrication system manufacturer should be able to provide you with the maximum values their system can handle while still lubricating effectively.
Are you running coil or blank stock?
How stock is fed into the press impacts your choice of system. This is especially true for contact type systems. For example, a roller applicator may depend on the movement of coil stock to rotate its rollers. For blank stock, you need a means to draw the stock through the lubricator. A powered roller solution may be required.
How wide is your material?
Naturally, your lubrication system should be able to accomodate the same stock widths your press is capable of accepting. Evaluate all current and future stock widths when making this consideration. Ask the lubrication system manufacturer if there are any performance issues or waste concerns when running narrow material through a system configured for wider stock.
How thick is your material?
For contact type lubrication systems, manufacturers should provide maximum and minimum values for stock thicknesses their system(s) can handle. Thicker stocks may require specialized systems designed to accommodate both the greater physical thickness of the stock and any loading/unloading concerns that accompany it. Ultra-thin stocks will require systems that can carefully lubricate without damaging the stock itself.
What are your automation and monitoring needs?
Want to know when your system is low on lubricant or when pressure drops? Want to automatically refill lubricant? Are you content with manually configuring lubrication settings from job to job or would you like to select from digital setups (jobs) stored in memory? Maybe you'd like your lubrication system to interface directly with your press controls. It's all possible depending on your lubrication system. Be sure to include any current or future monitoring or automation concerns when specifying your stamping lubrication system.
What lubricant will you be using?
Is your lubricant petroleum based? Synthetic or Semi-Synthetic? Is it water soluble? The formulation of your lubricant can impact your lubrication system's ability to apply it properly. Some lubricants may not be compatible with a system's seals or other components. Be sure to specify which lubricant(s) you plan to use with your lubrication system. A good lubrication system manufacturer will have data on your particular lubricant or will require a sample to ensure compatibility.
How will lubricant be supplied?
Fluid supply is an important consideration. Are you content to manually refill lubricant as needed or would your process benefit from automatic refilling? Do you have a central lubricant supply your system can utilize? There are many options available including fully automatic mixing systems that supply lubricant directly to your lubrication system. Depending on your operation, an investment in an automatic fluid mixing and supply system can pay off in efficiency and profit.
Hopefully the concepts outlined above will help guide you in your quest for the perfect metal stamping lubrication application system. Time spent considering this often-overlooked aspect of stamping will pay large dividends in terms of cleaner, safer work environments, reduced costs, and improved consistency and efficiency. Feel free to contact Unist to explore these concepts further. Our experts are eager to hear about your application and can answer any questions!