Preventing production stops

Today, more and more companies are relying on automated processes for their production. This is causing a shift in the root causes of one of the seven wastes – waiting. From the traditional influence of the production operator to chance-dependent “random causes” of micro-stops and failures that are hard to prevent. But are the causes of unplanned stops really so random and unpredictable that we can’t prevent them with simple methods? We will try to answer this question in the article.

Changing conditions in the production process

“If I knew I was going to fall, I would have laid down.” This sentence, along with “it was going well and suddenly it broke down,” “this machine just works that way,” or “the material is to blame,” or variations thereof, could be a standard list of answers in an operator interview form about process problems. Unfortunately, the sad fact is that both operators and mechanics are unable to provide any other information. The reason for this is the constant variability of the conditions under which the production process takes place.

Conditions, causing variability are:

• Environmental conditions (such as temperature or humidity).
• Fluctuations in material parameters (such as density or stickiness).
• Gradually increasing process dirt.
• Gradually deteriorating machine condition (due to wear and tear).
• Process adjustments made by the operator.
• Changes to the machine due to the need for repairs (for example, to non-original parts).

Thankfully, most processes show great resistance to fluctuations in the above conditions, and single minor changes do not immediately destabilize the process. Unfortunately, most of these changes occur continuously and simultaneously, resulting in disturbances that destabilize our process in various directions. Every once in a while, there is an accumulation of disturbances in one direction, causing the process to swing beyond the limits of stability, resulting in the machine stopping or slowing down. This is how waste is born. The greater the losses, the greater our cost in time, people, utilities and sacrificed profit on the product that could have left our production line at that time.

Stabilization of environmental conditions

Stabilizing environmental conditions, especially in areas with highly variable climatic conditions, is very difficult. It also often involves large financial outlays. Relying 100% on stabilizing materials that come from our suppliers makes little sense. They are likely to struggle with similar problems. In addition, there are provisions in commercial contracts for tolerance criteria that in most cases we simply have to agree to.

What can we do in such a situation to eliminate the waste associated with breakdowns and micro-downtime from our production? The solution is simple: we need to remove variability from our machines. How do we do it? Learn 3 steps to a stable manufacturing process.

3 steps to a stable manufacturing process

Establish standards for cleaning the production line

The first step is always to keep the machine clean. In cleaning, the most important thing is to keep process-critical areas clean. These will be dirt that gradually causes parts to lock up, affect sensor malfunctions or even lead to faster wear of parts in the machine. In our production, we should anticipate machine cleaning intervals and rigidly stick to them.

Cleaning schedules and instructions should be developed together with production operators and reviewed together with them. Such a solution not only shows production workers that cleaning is an important process for the organization, but also builds their motivation to maintain self-discipline in performing these activities.

Inspection of machine condition and process safety

Once the machine cleaning standards have been established and the 5S or Machine Day workshops have been conducted, we can proceed to the next step. Step two is to ensure machine condition control and process safety.

In the context of manufacturing processes, anomalies are defined as all symptoms of deviation from the best condition of a machine or system, as well as all solutions that make it difficult for us to run the process stably. In TPM (Total Productive Maintenance which you can read more about here) we talk about seven types of anomalies.

7 types of anomalies in TPM:

1. Minor defects
2. Unfulfilled baseline conditions
3. Places that are difficult to access
4. Sources of contamination
5. Sources of quality defects
6. Unnecessary items
7. Dangerous places

These anomalies should be detected on an ongoing basis (e.g., during routine cleaning of the machine), reported and corrected as soon as possible. This prevents serious failures and malfunctions in the future.

Establish parameters for stable work

The third step in stabilizing the production process is to establish parameters for stable operation. This is extremely important. Why? Because by adjusting the parameters each time, we introduce a disturbance into the process, which may later cause the need for adjustment elsewhere.

Operating parameters are stabilized gradually. An immediate ban on changing process settings can be counterproductive in this type of project. We must remember that adjustments are made in response to changes in conditions over which we have no control. Therefore, it is good practice to establish parameter adjustment ranges.

Inspection of machine parameters

However, it is not enough to standardize the parameters of the machine. For this action to have the intended effect, we must control these parameters. How? Controls can be implemented through TPM rounds, which you can learn more about in the Total Productive Maintenance – TPM course. During these rounds, the machine operator checks individual control points on the line. Since this is an activity that takes up employee resources, care must be taken to ensure that the values being inspected are properly highlighted. The easiest way to ensure this is to use visual inspections. They allow you to assess the value of a process parameter “at a glance”, thus eliminating the need to compare values with ranges written out on a form and greatly speeding up the inspection process.

Unfortunately, even in the best-parameterized process, there may be a situation in which the operator has to move a value outside the acceptable range. This usually happens when an unnoticed disturbance begins to build up in the process. Such situations should be recorded and analyzed on an ongoing basis. Failure to analyze even minor problems can lead to gradual destabilization of the production process after some time.

Maintain stability

Implementation of the above steps is fundamental in maintaining a stable production process. The 3 steps to a stable manufacturing process allow you to maximize profits by minimizing the amount of unplanned downtime (or eliminating it altogether). By stabilizing the production line, we further facilitate the identification of the root causes of problems faced in the production environment.

However, it should be emphasized that the above-described measures should not be applied once, but should form the basis for further measures to improve production processes.