Tag: synthetic fluids

Considerations for Coolant Selection

Posted on by Twin Specialties in Blog Tagged , , , , , ,

Finding the optimal metalworking fluid is a difficult task because no fluid is “one-size-fits-all.” Each shop has its own unique set up of machines, operations, metals, etc. Operators have to consider many factors before selecting the optimal fluids or fluids for their shop. The optimal fluids should successfully perform the following core functions:

  • Lubricate the cutting edge
  • Disperse heat from the cutting edge and workpiece
  • Flush away chips from the cutting edge

Additionally, there are secondary functions a coolant can improve your operations. These include:

  • Corrosion protection
  • Extending tool life
  • Reducing energy consumption and machining forces
  • Improve surface finishing

To find a coolant that can perform these functions, you should take the following factors into consideration.

Machine Requirements

The types of machines in your shop will determine what type of fluid you will need. Older, swiss-type lathes can use neat oils. Whereas newer and more sophisticated CNC mills and lathes perform better with a water-soluble product. This is because higher speeds and higher pressures need more cooling than swiss-type lathes. The water does an excellent job cooling the cutting edge and workpiece. For neat oils, the cutting diameter plays a key role in determining the appropriate viscosity. The smaller the diameter, the lighter the viscosity should be to maintain and improve flow characteristics.

If your machine is operating at high speeds and/or high pressures, it is wise to consider a low-foam coolant or a specialized “high-pressure” coolant to use. Synthetic coolants are also an option as they tend to have lower foam rates than semi-synthetic and soluble oils. If your shop has a wide variety of machines and operations, you can consider using different fluids that are tailored to each operation. Over-consolidation can cause issues and may not be worth the savings. Fluids can be bought in smaller quantities and be used in limited cases to ensure performance and tolerances are met.

Shop Preferences

Machines do the heavy-lifting in metalworking, but there are still people behind each operation programming the CNC or working the lathe. Operators always get coolant spray on their skin and could be subjected to mist or spray. Finding a product that does not cause irritation nor spray/mist is paramount to keeping your operators safe and happy.

Shops have to consider the costs and labor involved in changing fluids as well as maintaining fluids. Cheaper fluids may save money, but will require more maintenance, monitoring, and change-outs. If your time is limited, investing in higher cost fluids will free up time to complete other machining tasks.

The ancillary equipment in the shop also can influence what type of fluid you need. If your sumps are equipped with oil skimmers, paying extra for a fluid with advanced tramp-oil-rejection characteristics may be unnecessary. Automatic mixers makes synthetic coolants a more attractive option since the concentration control required for synthetics is much more stringent than semi-synthetics and soluble oils. Understanding what is in your shop will help determine what fluid is appropriate for you.

Operations and Water Quality

As mentioned before, operations with higher speeds and pressures will call for a fluid with robust extreme-pressure (EP) additives to cut the toughest metals. In slower operations, a soluble or neat oil can be sufficient.

Your shop’s location will play a key role and fluid selection since the tap water is different in each town. If your shop has harder tap water, your machining might be negatively affected with higher chloride and sulfur content. Softer water is susceptible to more foaming. Avoid using softer water in higher pressure machining to limit foaming issues. It is recommended to charge up a sump with tap water and then use deionized (DI) water for topping off the sump and maintenance.

Shops can install a DI-Water line that can hook right up to an automatic mixer and improve coolant mixing. Distributors, like Twin Specialties, offer water testing services in the context of metalworking fluids. We can learn more about your water and make product and operational recommendations to improve coolant performance.

Workpiece Materials

Not all metals are the same. Some are soft, some are hard. Some metals are more reactive and require more care and specialized fluids. Magnesium requires certain additives or fluids that designed to machine magnesium. When machining carbide, it is best to use an amine-free coolant that does not react with the carbide and result in cobalt leaching. Harder metals like Inconel or titanium require coolants with EP additives and superior cooling to ensure heat is dispersed and friction is reduced. If you machine titanium or exotic metals in limited circumstances, it may be beneficial to keep a pail or a few gallons of a robust coolant in storage used specifically for those jobs and operations.

Potential Contamination

Contamination can occur frequently and in many forms. The main contaminants to watch for are: oxidation, tramp oil, and biologics. To combat oxidation, many fluids have anti-oxidant additives. It is key to monitor temperature as excessive heat will oxidize the oil. Antioxidants are limited in coolants; once all of the additive is consumed, the oil degrades quickly and will need be replaced sooner rather than later.

Tramp oils can change the oil’s viscosity, thus its flow characteristics. Having coolants with tramp-oil-rejecting compounds will help, but using oil skimmers is an excellent option to combat tramp oil. The skimmers remove the oil off the top of the sump and limits tramp oil being circulated through the machine. Oil filters are recommended to keep tramp oil from circulating through the system. Neat oil systems should use 5 micron filters and coolant systems should use 15 micron filters.

Outside biological contamination like bacteria can wreak havoc on your machine and cause clogs and ruin your fluid. Many fluids contain biocide additives to combat bacteria, but many factors allow it to grow uncontrolled. Be mindful to thoroughly clean your machine before recharging it. Any remnants of bacteria will multiply and ruin your fluid. Hot operating environments spur bacteria growth so it is recommended to implement as much climate-control in your shop as possible. Circulating the coolant will also make it tougher for bacteria to grow. Tank-side biocide additives like Grotan can supplement fluids and fight bacteria. Ensuring your coolant has proper concentration will ensure there is enough biocide to prevent bacteria growth.

Concentration

Monitoring concentration is key for maintaining your fluid. Some fluids, like synthetics, require tighter control and more monitoring. If you are limited by time, using a soluble or neat oil will reduce the time needed to monitor your fluid. Coolants typically run between 5 to 15% concentration. Using a refractometer to regularly track concentration is the best way to monitor and maintain coolants. Technical data sheets include refractometer charts and BRIX factor information to ensure the coolant is mixed optimally. If the line in the refractometer is blurry, that is a sign of contamination in the sump. Automatic mixers are ideal for charging sumps and eliminate human error or measuring biases that may occur when mixing coolant.

Takeaways

Selecting a metalworking fluid is a thorough and long process. Taking these considerations into account will set you up for long-term stability and success. Working with a metalworking fluid distributor and/or manufacturer is strongly recommended to help select to correct product. Twin Specialties offers a wide range of metalworking fluids and fluid maintenance resources to ensure you get the most out of your fluid.

5 Factors for Drawing Fluid Selection

Posted on by Twin Specialties in Blog Tagged , , , , , , , , ,

In drawing processes, there two main types of lubrication. Firstly, there is fluid or hydrodynamic lubrication, which is the separation of metal surfaces with a continuous film of lubricant that prevents contact of those metal surfaces. Secondly, there is boundary lubrication, which is separating metal surfaces by a film only a few molecules thick.

The drawing process generates extreme pressures and the lubricant needs to perform to ensure proper separation of metal surfaces.

Factors for Drawing Fluid Selection

There are many factors that will affect lubricant selection. We will examine these factors and how they may affect lubricant selection and use. Considering these factors will ensure proper separation and excellent performance.

Type of Metal

Not all metals are alike. The first classification for metals is whether it is ferrous, non-ferrous, or an alloy. The hardness of metal will also be a key factor. Harder metals will require higher pressures, thus higher operating temperatures. A harder metal will need a lubricant that provides excellent cooling to prevent poor finishes or melting. Resistance to rust and corrosion varies metal to metal. Porous metals, such as cast iron, are porous and can rust quickly during annealing. Applications with those kinds of metals may require a lubricant that has rust/corrosion preventative additives.

Severity of Operations

The severity of the operation will be key to determining what kind of lubricant you need. Operations with extreme pressures may require lubricants with extreme-pressure and anti-wear additives to maintain proper lubrication. Operating speeds play a key role in determining the viscosity needed. Higher speeds will require lower viscosities so that the lubricant will adequately circulate. As temperatures rise, viscosity can degrade quickly. When the lubricant becomes too “thin” or “runny”, proper separation may be lost. Some lubricants will include viscosity index (VI) improvers to help maintain proper fluid thickness as temperatures rise.

Tooling

The tooling used in drawing may affect the lubricant selection. Some of the tools used in drawing include:

  1. Dies for cold drawing
  2. Rolls for forming strips and shapes
  3. Cutting tools
  4. Extrusion dies
  5. Heading dies
  6. Plugs
  7. Mandrels

The material of the tools also matters. In high temperatures, tool life may diminish and a lubricant that extends tool life improves performance and reduce costs. Tooling can be made of the following materials:

  1. Steel
  2. Carbide
  3. Diamond (synthetic or natural)

Subsequent Processes and Applications

Once a workpiece has completed the metal working process, most likely it still has to go through more manufacturing processes. Some of these include: annealing, cleaning, painting, and assembly into the final product. Cleaning the workpiece is import for final assembly as you want to avoid rust and corrosion. Drawing fluids that are emulsifiable are easier to clean and are preferred by some manufacturers. The cleaning process used also matters. Whether you use a dip tank, spray washer, or vapor degreaser, selecting a fluid that can wash away while also reducing rust and corrosion will be dependent on the cleaning process. Many fluid manufacturers, such as Twin Specialties, supply cleaners that are developed with their drawing fluids in mind.

Economic Considerations

With limited budgets, manufacturers must be pragmatic in selecting a fluid. Opting for a less expensive product may have hidden costs that are not realized at time of purchase. Lower quality fluids may reduce tool life and the fluid itself may need to be changed more frequently. These costs can add up and may not be realized until the job is completed. If your budget allows for it, opting for a synthetic fluid may prove to be a smart choice. Even though lubricants do not make up most of the budget, selecting the right lubricant can create tremendous cost savings on other parts of the income statement.

Takeaways

Each manufacturer has unique conditions and budgets; thus, no lubricant can be a one-size-fits-all product. Analyzing your metal workpieces, operations, tooling, cleaning and assembly processes, and budget will provide clarity. That clarity can aid lubricant selection and allow you to focus more on your manufacturing.

Working with manufacturers and distributors to determine the proper lubricant is the best strategy to maximize efficiency and boost the bottom line. Twin Specialties can analyze your processes and budget considerations to find the optimal lubricant.