Advantages of Intelligent Press & Automation Controls Over PLCs in Stamping Operations
Intelligent press production systems engineered specifically for stamping presses have a number of critical and clear advantages over PLC implementations.
While PLCs are commonly used for a variety of machine control applications, there are numerous reasons why generic PLC hardware should not be used for press control applications. To do so is inadvisable at best, and possibly dangerous. Approaching a press control project “from scratch” without a thorough understanding of the standards and fundamental requirements of safe and reliable control for presses can require a significant amount of time, and it presents potential liabilities and extraordinary challenges for even experienced programmers.
Additionally, each unique press subsystem (lubes, hydraulic overloads, pneumatic control and monitoring, specialized modes, etc.) must be individually accounted for and properly implemented.
Approaching a press production system project by utilizing press and automation controls that have been specifically engineered to be easily configurable for safely controlling the stroking of the press, and also configurable for control and monitoring of subsystems that are common to stamping operations, is a smart decision for manufacturers. It can save significant implementation time in the field but also help to ensure reliability, repeatability, and greatly increase the likelihood of useful diagnostics.
Of course, properly engineered press control systems are a necessity for control of the clutch and brake, where safety standards and regulations are a key consideration. However, a successful implementation of a press production system project is typically far more than just clutch and brake control considerations. The control and monitoring of critical press subsystems, such as hydraulic overloads, lubrication systems, cushions, counter balances, motor control systems and others must also be taken into consideration.
Here’s where a composite press production system control that has been specifically engineered with the overall needs of stamping press controls in mind can easily pay for itself many times over. Let’s dig a little deeper into some of these clear and important advantages.
Safety & Compliance
OSHA 1910.217 spells out specific considerations for the design and construction of part revolution mechanical power press controls, including the concept of “control reliability.” The need for control reliability is also part of the standards for mechanical power presses in ANSI B11.1.
Link Systems has been instrumental in contributing to those standards for the metalforming industry for many years. It is important for anyone considering designing or implementing a press production system to know that control reliability for a mechanical power press control cannot be achieved with a simple, single PLC. There is a thorough discussion of why this is true in Appendix D of ANSI B11.1.
For the engineer who may wish to attempt an “in-house” design of mechanical power press control using (for example) two PLCs to try to achieve control reliability through “redundancy” or “cross-checking,” there are multiple reasons why this approach requires careful consideration. This includes the fact that the requirement for control reliability extends beyond the processor and its control algorithm to other control elements and the treatment of sensors such as the press crankshaft angle transducer, valve monitors, etc. The specialized knowledge and expertise required to successfully implement true control reliability means there is a considerable risk that an in-house design will fail to meet the rigorous standards.
The best approach is to choose a purpose-built, safe, reliable press production system that will meet all applicable regulations and standards. Choose an experienced, knowledgeable press control partner who meets the applicable standards, stands by their design, and tailors it to meet your specific application. Link Systems is such a partner.
Every application for a press production system presents a unique set of challenges and considerations for a successful implementation of the overall control. While every mechanical power press “makes strokes” and “produces parts,” there can be extraordinary differences from one press line application to the next, even when looking at two similar machines from the same press manufacturer.
These differences may include press subsystems such as lubes, hydraulic overloads, shut-height setup mechanisms, clutch-brake configuration, flywheel brakes and the like. They may also include external press line equipment and systems, such as servo-feeds, transfers, robotics, and other automation. It may include die-clamping systems, moving bolsters, or scrap removal systems, or any number of auxiliary control considerations.
Some presses may be manually stroked by an operator or multiple operators for some jobs, while relying on a more automated process for others.
To account for the breadth of applications seen in even small press shops using PLCs would require a monumental coordinated effort with an individual approach for each machine in order to analyze, design, and implement controls correctly. It is unlikely that even experienced PLC programmers have the specialized knowledge and experience to successfully, safely, (and frankly, legally) implement press controls.
Given the wide variety of processes, subsystems, and equipment that may be found in press production systems, having a purpose-built control that meets all applicable standards is a huge advantage. The control should also be easily configurable for the direct control and monitoring of many subsystems, and relatively easy to integrate with external control for other auxiliary control components.
These benefits extend beyond ease of design and efficiencies during implementation and startup. There are also tremendous benefits for the manufacturer in the standardization of control hardware and user interface throughout the pressroom.
When problems or error conditions occur in PLC-based implementations, it often is necessary for maintenance personnel to utilize a programming terminal or console to diagnose and troubleshoot the problem. It can be a time consuming and inefficient process, especially considering the number and types of systems on even relatively simple presses.
Most one-off implementations of systems using PLCs do not have adequate diagnostics and troubleshooting built in to their systems. Indeed, it is relatively common that there may not be any sort of routine or basic diagnostics built in. There may be no information readily and intuitively available about the status of inputs and outputs to the control, the functioning of program routines, etc.
A purpose-built system, such as the Link 5100 series of press and automation controls, has extensive and highly detailed diagnostic functions built in. Additionally, with the ability to recall job settings, limit access to trained and authorized employees, and provide on-screen monitoring for all critical press functions, users now have a real-time window into what is happening in the system.
Another typical downside of PLC implementations is that there may tend to be variation in the controls from machine to machine depending on who did the programming and when they did it. Additionally, program changes can be and often are made without proper documentation or, worse, without proper understanding of the existing system design and regulatory requirements.
Hardware on different presses may also be different depending on what was current at the time. These factors present multiple challenges for timely troubleshooting of problems to ensure low downtime for critical processes. It can also be costly in terms of amount and variety of hardware needed to have adequate on-hand spare modules, etc.
Purpose-built intelligent press controls, such as the Link 5100 series controls, are designed and tested with standardization and longevity in mind. Because Link designs and manufactures all its own circuit boards and products, we can do our best to ensure short deliveries of standard replacement/repair components and at the same time offer the longest product life cycles in the industry. Additionally, Link has reasonable upgrade paths for even its most mature product offerings.
Engineered press controls will likely have additional functions commonly used in stamping operations. These can include modules for die protection, tonnage monitoring, programmable limit switches, automatic setup of critical settings, and others.
Because the provision for these functions is already integrated and tested, they require no special programming and dramatically reduce implementation time and troubleshooting. Modular design with distributed processing allows additional modules to be easily added to ensure your press production system grows with press production needs.
Take the Next Step to Improving Productivity in Your Stamping Operations
Link Systems and its dealer network have a vast depth of experience in the stamping industry. Contact us today to speak with a Link press and automation controls expert who can provide an in-depth evaluation of your current stamping operations.
Download this white paper to learn how intelligent controls can help you maximize efficiency, reduce downtime, ensure proper preventative maintenance, and improve your bottom line.