Power presses are the fundamental basis of sheet metal forming operations due to their ability to provide speed, accuracy, and repeatability at a high volume. One aspect that typically goes unnoticed in regards to performance is the effect of temperature on the machine. Constant operation of the machines, heat created by friction between components and components and by their operating environment will have an impact on how accurately, efficiently and positively the power press operates during its whole life span. Therefore, for Power press machine manufacturer wishing to produce Quality components, with reduced downtimes, an understanding of and control over thermal effects is vital.
Understanding Thermal Build-Up in Power Press Machines
When operating for long periods, different parts of a power press can produce heat from the friction and mechanical work of the machine parts. Some parts are more prone to heating up than others, like the crankshaft, bearings, clutch mechanism, and sliding surfaces. In addition, the action of the ram repeatedly moving back and forth is the primary source of internal heat in a mechanical press. By contrast, a hydraulic press develops heat from the compression of fluid within the hydraulic system and from the circulation of that fluid as well. Factors outside the machine, such as outside air temperature and lack of proper ventilation, can also add to the generation of heat in the power press.
Impact on Machine Accuracy and Precision
One of the main effects of heat being produced from thermal expansion is that as components heat they also expand; therefore causing dimensional changes, which will alter how aligned and tolerant an assembly will be. When components do not line up or have incorrect tolerances, slight deviations from the expected measurement will create problems with bending and stamping of parts or with not having proper clearance when using dies. In the long run this will negatively impact on the quality of product manufacture, particularly in applications requiring close tolerancing such as the automobile or aerospace industries.
Effect on Tooling and Die Life
The heat in most cases causes machine and tooling failures. Tooling can include many different components such as punches or dies. These components are subject to a lot of mechanical loads and high temperatures, resulting in premature wear out of these components, as well as reducing the usable life of them. Tooling can fail due to plumbing deformation on the tooling material, creating warped, cracked or prematurely defective tooling. Better thermal management practices will extend the service life of tooling due to reduced maintenance costs and less downtime in the production process.
Influence on Lubrication and Friction
The function of lubricants is to lessen the amount of friction that exists between two moving surfaces. Due to elevated temperatures, lubrication loses its performance and helps to increase the amount of friction that occurs, producing more heat and creating a negative feedback loop of accelerated wear. Additionally, when the lubricant is insufficient at elevated temperatures, component seizure may occur, leading to surprise machine failures.
Energy Efficiency and Performance Stability
Power press machines’ effectiveness in terms of energy use can also be influenced by thermal effects. The greater the absolute temperature during operation of a power press machine, the higher the mechanical resistance experienced, and therefore, the greater the amount of energy required to achieve the same operational performance level. Hydraulic systems also experience decreased efficiency and less ability for pressure to remain stable with oil that is heated up to an unacceptable temperature range. If the hydraulic press brake machine becomes less efficient then operational cost will increase as the time passes.
Thermal Stress and Structural Integrity
If the hydraulic press brake machines are used excessively or overused then they might develop thermal stress and have high risk of heating. Such thermal stress may cause micro-cracking of the materials, fatigue of the material, and ultimately lead to failure of the structure itself. Components that are critical to the machine, including frames and connecting rods, are particularly prone to this phenomenon especially in high tonnage applications. Eventually, this type of wear will also result in the machine becoming less stable and safe.
Methods to Control Thermal Effects
Thermal management can play an important role in the performance of equipment; therefore, manufacturers and operators should develop their own thermal management strategies. For example, lubricants made from heat-resistant oils should be used as part of the lubrication systems to maintain functional performance at elevated temperature operations. Cooling systems such as air or oil coolers can be installed during initial equipment manufacture to aid reduction in heat buildup on products. Performing regular maintenance that involves checking bearings and moving parts will allow for timely identification of potential heat problems before they occur.
Furthermore, current day power press machines are becoming more and more likely to include temp sensors and demag sensors for monitoring purposes. Temperature monitoring systems provide instantaneous feedback on thermal conditions enabling operators to make preemptive measures when problems arise. In addition, optimizing the cycle time of the production cycle and avoiding excessive overloads also support continuous stability of the operating temperature.
Future Trends in Thermal Management
Smart technologies are being accepted to handle thermal problems for power press manufacturers working in an Industry 4.0 environment. Predictive maintenance systems using IoT based sensors will help to study temperature behavior or changes to anticipate future issues. In addition, manufacturers are using advanced material that has superior heat resistance (thermal capabilities) and thermal conductivity properties to allow for greater press machine life span. These advances have led to greater reliability and efficiency of today’s press machines in our modern manufacturing environment.
Conclusion
Power press machines operate under many conditions that cause thermal solutions to impact power press machine performance, accuracy, and lifespan. These conditions result in impact on dimensional accuracy as well as reduction of tool life due to increased energy usage when heat has not been effectively managed. Manufacturers of power presses must effectively manage heat generated by their machines to maximize productivity, reliability and efficiency of the machines and avoid performance decline as time passes due to thermal accumulation. Therefore, knowing what causes thermal accumulation, its effects and how to control it is crucial for the optimal operation of the equipment. With technology continually advancing and manufacturers always looking for improved methods to manage the heat generated by their systems, there will be greater demand for thermal management solutions as manufacturers work to operate at increased levels of productivity while maintaining competitiveness in a global marketplace.