Reduce manufacturing lead time
Manufacturing lead time is a measure of how long it takes to create a product from the time the order is received by a manufacturer until the product is shipped. If through automation the manufacturing lead time is reduced for a process or a series of processes, output will increase over a given time period. If all other inputs remain unchanged, productivity will increase.
Some other reasons for automation often referenced in the literature, which are tied indirectly to productivity, include: (1) the high cost of not automating and (2) the existence of processes that simply cannot be done manually. The first is a somewhat obvious statement, regarding which the above list makes a strong case. In today’s economy productivity improvements are perhaps the only way to remain competitive. If a company is not competitive, it will not survive. Therefore, the cost of not automating will be in terms of lost customers and profits.
Consider the second of these, performing processes that cannot be done manually. Some processes may require too high of a degree of precision or be too small for the human hand to effect or have too complex a geometry. Ponder the manufacture of computer chips. Arun Radhakrishnan, writing in http://blogs.techrepublic.com.com/tech-news/?p=2050), pointed out that in 2008 Intel announced a new computer chip containing 2 billion transistors. Obviously, this can only be produced with the aid of automated machines; without the automation to manufacture it, the product could not be made and thus productivity would be zero.
Thus, there may be many reasons to automate, but the primary benefit to automating is improved productivity. When a company continuously improves productivity it is better able to absorb raw material cost increases, labor cost increases, increased energy prices, and other inflationary types of cost pressures—without passing those increases along to the customer. Thus, by improving productivity the company may realize other benefits including higher sales, better customer relations, and a larger market share. Although automation is not the only method to improve productivity, it is often a very effective method and should therefore be strongly investigated.
The why and where of automation are listed in the preceding section. We now turn to the how of automation. Typically, how a plant would automate is one of the more challenging aspects of the automation implementation process. One example was given already, that of employing a robot to perform material handling or adding a PLC to control the process. It is the intent of this section to provide some strategies that can be used to determine how a particular process might be automated.
In the aforementioned Automation, Production Systems, and Computer-Aided Manufacturing, 2nd ed. Groover introduced 10 strategies concerning how automation can be applied to manufacturing processes. Based on this list, five condensed “how to” strategies, geared specifically for programmable automation, are given here:
Minimize manufacturing process steps
As explained, a series of manufacturing process steps convert raw materials into some other higher value form. This strategy seeks to minimize the number of process steps. It does so by combining process steps, as might be done by the performance of more than one process on a single machine. Once operations are combined, it may then be possible to perform processes simultaneously. If processes cannot be combined, it may be possible to integrate several processes into a single machine or work cell. The integration could be in the form of several machines linked together with automated material handling devices. Thus, the cell will have the appearance of a single machine. Whichever method is used the result is the same: manufacturing process steps are minimized. Minimizing process steps can lead to large productivity gains by reducing input to the process and perhaps improving output rates from the minimized process.
Increase process flexibility
Improving process flexibility enables a machine or operation to process more product variety. The flexibility is achieved by minimizing or eliminating setup time typically required in changing a machine over to another product line. This is the essence of flexible automation systems. When a particular machine is able to process more product variety, the machine’s utilization increases, manufacturing lead time decreases and work in process is reduced. This can result in a substantial increase in productivity because inputs (time, labor, ...) are reduced, assuming of course that system output remains the same or increases. This strategy will also likely involve use of the all three programmable automation technologies.
Optimize material handling
Material handling is a non-value-added component of the material conversion process and thus should be optimized. Machines can often move material more consistently, accurately, and reliably than manual labor. Additionally, labor, freed up from performing material handling tasks can be displaced to perform value-added tasks. Thus, the increase in productivity may come from reduced labor costs, increased production rates, and reduction in scrap and rework. Optimizing material handling may involve a combination of mechanical technology systems, including conveyor systems, indexing units, and pick-n-place units, with robotic and PLC technologies.
Automate inspection
Product inspection determines if a product is within specifications. Often performed offline or outside of the process, inspection gives feedback about how a process is performing, and information gathered from inspection is typically used to adjust a process as needed. The feedback loop—make a part, inspect it, adjust process—can be rather long. Hence, products outside of specification (“off spec”) could be completed before the process that made them is adjusted. Automatic inspection is an attempt to minimize the feedback loop and thereby reduce scrap and rework. And, of course, a more consistent, higher quality product is produced. To sum up, raw material usage is reduced and output is increased, resulting in substantial productivity improvements. Automatic inspection systems may utilize material handling technology, including robotics, electronic vision systems, electronic sensors, actuators, and PLC technology.
Implement process control
To produce a high quality product it is necessary to have a consistent, repeatable, and reliable process. To achieve this, a process must be rigorously controlled. Programmable logic controllers are capable of providing this level of control, providing it over event-driven changes to the process. Based on the status of these events, the PLC will make decisions and take appropriate action on the system. This enables fast, reliable control of the process and greatly improves its efficiency. In addition to greater efficiency, process output and product quality are also improved.
Note that a particular automation project may focus on only one strategy or include all five. Keep in mind that not all processes can or should be automated. Some processes may be too technologically difficult to economically automate. For others, the product life cycle is so short that automation cannot be justified. In some cases it may appear that the cost of the automation is completely justified based on the anticipated productivity improvements, but later it may be discovered that is simply not the case. Thus, it is imperative one have a sound method of justifying where and when to use automation. The next chapter deals with this subject in detail.
Programmable automation technology is the combination of mechanical, electrical, and computer technology developed to have very specific automation capabilities. Programmable automation consists of three individual technologies that are linked together by their capacity
