Coolants, lubricants, and other fluids used in manufacturing may sometimes seem to be a production bottleneck, restricting productivity or performance. Often the resolution won’t be found in costly chemical alterations to the fluid itself, but simply a better understanding and control of the factors affecting performance.
Here are four of the factors that can influence fluid performance and how to manage them.
1. External environment
It is a little-known fact that the production environment, and particularly temperature, can have a significant impact on the performance of fluids. A production plant operating in a cold climate will need a whole different set of parameters to one operating in a warm one, for the same application and fluid. The temperature changes do not have to be extreme though; a shift of just a few degrees from the morning to the afternoon is enough to disrupt what had been a steady production process. In a traditional setting, often this will lead to a lengthy reset as parameters are reviewed and adjusted to achieve optimal performance.
There are some practical steps that can be taken to reduce the impact of the external environment. Ensuring fluid is stored as close to the dispenser as possible is one option, as this will drastically reduce the time that the fluid is outside of a controlled environment. And, insulated feed lines can further mitigate any temperature fluctuations.
2. Internal environment
Mitigating the impact of the external climate is an important first step. However, that will be successful only if you’re able to maintain a consistent internal temperature during production.
A lack of internal temperature control during production can lead to inconsistent performance, parts failure, and machine downtime. Too often, manufacturers and machine builders will turn to their fluid supplier when they encounter such problems. In fact, taking a closer look at the internal environment of the production line often will lead to better results, much quicker and at a fraction of the cost.
While a lot of attention is given to dispensing, industrial fluids can spend as much as 90% of production time in the reservoir. Full temperature control at this stage not only ensures consistency at the point of use but can also enable operators and line builders to optimize fluid performance, reduce waste and eliminate fluid related parts failure.
3. The top-to-bottom effect
Surprisingly, the top-to-bottom effect has been fully investigated by scientists and engineers only in the last few years. Essentially, it gives an indication as to why a fluid’s performance changes dependent on the amount that remains in the container when all other parameters are set. In manufacturing terms, operators have long noticed a steadily decreasing flow rate when using a time / pressure system.
The top-to-bottom effect is caused by the constant change in volumes of air and fluid inside the vessel. As the fluid level goes down inside the vessel, the volume of air increases but the ratio of compressed air, at a given pressure is not linear in comparison to that of the fluid.
To put it simply, at constant pressure, an increasing volume of compressed-air cannot sustain a consistent pressure on a fluid, therefore generating a different amount of force. This can be understood when you consider one of the fundamental differences between pneumatic and hydraulic law, namely, that air is indefinitely compressible whereas water and a vast majority of fluids are not. As such, air is always the variable and yet it is an essential part of a process that requires consistency.
The solution to this can be pieced together by a determining the right-sized vessel and managing the pressure in a more precise way, enabling control over the amount of compressed air inside the tank, to deliver a consistent amount of force.
4. Agitation
One of the other major impacts on the chemical composition and performance of fluids is movement – whether that be too much movement or too little. These are known as thixotropic fluids. Examples include anything from UV adhesives, epoxies, silicone, RTV (room temperature vulcanizing), rubber sealants, and heat sink compounds.
Thixotropic fluids are more common than you would think, as anyone who has had the ‘pleasure’ of wallpapering or painting a room can attest. Both paint and wallpaper paste are significantly affected by movement, the latter being the best example. The paste is often difficult to stir at first but the more you stir, the easier it becomes to mix. What is happening here is that the viscosity of the material is changing as a result of the movement applied to it.
While this might not be so much of an issue for those doing home décor, in a production setting it can lead to dramatic inconsistencies resulting in too much or not enough material being added to parts which may then have to be reworked, cleaned, or in some cases even scrapped.
The answer lies in viscosity control through agitation. This can be either set as a fixed parameter for a full production day, or coupled with sensors to adjust to changes within the fluid itself.
Fluid handling needn’t be rocket science. Controlling, monitoring, and adjusting parameters where needed will enable continuous improvement, reduced waste and a significant reduction in unplanned downtime.
Loris Medart, general manager of SR-TEK Ltd., a manufacturer of pressure and pressureless tanks, agitated systems and pumps, is the author of a newly released report, The Complete Guide to Fluid Management, available for free download.
