Identify Complex Tasks And Simplify Them

This issue's time saver is a rather general suggestion - and it varies with the aptitude level of the people involved.


In value added terms, there are only two types of tasks that occur in the manufacturing environment: those that further the completion of your product and those that don't. Tasks that further the completion of your product are called value added tasks. Those that do not are called necessary support tasks.


Any improvement you make in your company should be aimed at either enhancing a value added task or minimizing or eliminating a necessary support task. In either case, task simplification should be one of your primary tactics for improving.


By "complex task", we mean a task that is causing problems - and they should be pretty simple to spot, especially with tasks that directly affect value added tasks. Scrap parts, wasted time, duplicated effort, and damaged machines are severe symptoms of complex tasks that are too complicated for your people to perform.


Here is a simple example. CNC operators are charged with the responsibility of measuring workpieces during the production run. They compare these measured dimensions to the tolerances specified on the blueprint. They then make a decision. If the measured dimension is well within its tolerance band, they do nothing. But if the dimension is close to the high or low limit (based upon how the tool wears), they make an offset adjustment. The amount and polarity of the adjustment must, of course, be calculated before the adjustment can be made.


This task of workpiece sizing during the production run is a necessary support task - it does not further the completion of the workpiece. But of course, if a mistake is made, it can adversely affect the performing of a value added task. The next workpiece being machined will not be within tolerance. A drastic mistake can be even worse - a cutting tool may crash into the workpiece.


This is but one of countless tasks that operators must perform. Most of these tasks are necessary support tasks, but again, mistakes will lead to problems with value added tasks. And even if mistakes are not made, it takes time to perform these tasks. Simplifying tasks an operator must perform will help them get to value added tasks quicker (reducing cycle time), it will provide them with more time to be doing other things, and/or it will reduce operator fatigue during a production run. Fresh and alert operators are less prone to make mistakes.


Your two alternatives

When faced with a complex task that is causing the kinds of problems mentioned above, you always have two alternatives.


1. You can provide more training to the person that performs the task. Again, people vary with aptitude. What one person thinks is easy another will find very difficult. One way to solve the problem of the complex task is to bring everyone up to a level at which they no longer find the task to be complex (anything is simple when you know how to do it!). Note that this doesn't address the time issue. I've often heard manufacturing people say that CNC operators should be able to calculate the target value (often the mean value) for all types of tolerances (+/-, high/low limit, and uneven plus versus minus). While I tend to agree that operators should be able to do this, why would we force them to take the time to do so - holding up production - if the task can be simplified or eliminated (by providing a target value for all print dimensions on a special process drawing).


2. You can simplify the task. I've been calling this the fast-food restaurant approach. When you order at the counter of a fast-food restaurant, you order a meal number. The attendant simply types that number on the cash-register and is told what to place in your bag and how much to charge you. When you pay, they type in the amount you've provided and are told how much change to give you back. Fast-food restaurants have made an art of task simplification. Just about anyone can work as a cashier with a minimum of training. Apply this thinking to your CNC environment. What can you do to simplify the tasks related to running CNC machines. Your four goals will be minimizing mistakes, reducing the time it takes to perform the task, minimizing the amount of training needed to get a person to the point that they are proficient, and making it possible for as many people to be able to perform the task as possible.


Remember, when you're faced with a complex task that is causing problems, you've got to do something. Providing additional training and task simplification are your only two alternatives!


A few specific suggestions

Our intention is for you to be able to locate, evaluate, and simplify complex tasks in your own CNC environment. And only by studying your own methods and watching your own people will you be able to do so. But to help get you started, we offer a few common tasks that often need simplifying.


Provide the target dimension for all dimensions - We mentioned this above. Entry-level operators must often use a calculator to determine the target value (often the mean value) for tolerances they must hold. This is time-consuming and error prone - and it leads to inconsistencies among operators (first, second, and/or third shift) even during the same production run. Eliminate calculation time, the potential for mistakes, and inconsistencies among operators by providing them with a process sheet that includes all target dimensions.


Specify all tolerances as plus or minus (+/-) - By far, the easiest form of tolerance to evaluate is the plus or minus tolerance. For the dimension 3.000 +/- 0.002, everyone will know that the specified value 3.000 is the mean (and often the target) value. If design engineers don't always specify tolerances this way, use a special process drawing to do so.


Provide the high and low limits for all dimensions - For the times when operators must determine whether a value is within the tolerance band (after measuring a workpiece), provide the high and low limits (3.002 / 2.998 for the 3.000 +/- 0.002 dimension) for the example above. This makes it much easier to determine whether a measured dimension is within the tolerance band - and when it has grown or shrunk close to a limit and is in need of an adjustment. So on your process drawings, you should provide three things for each dimension: the target value, the high limit, and the low limit.


Velcro small tools close to where they are needed - Don't make your operators scrounge through tool boxes in search of small hand tools (like Allen wrenches). Keep them handy by using Velcro to stick them in position close by where they are needed. For turning centers, for example, it will be helpful to Velcro insert-changing tools to each turret station in close proximity to the insert.

Use a consistent method for mounting jaws on three-jaw chucks - This is the topic of an article in the Summer 2004 issue of The Optional Stop newsletter. Please click the link to learn more about it.


Don't take no for an answer

As stated, when you are faced with a complex task that is causing problems, you must do something about it - otherwise you'll continue having the problems caused by the task. You can't give up. Either provide the training it takes to bring the people involved to a higher level or simplify the task.

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