I think the initial question was how to deal with operators who don't follow work instructions, a conversation I digressed into the validity of work instructions. While I still stand firm on my observations over time as well as my formulated opinion based on those observations. They only answer one of the causes related to employees not following work instructions.
To answer the initial post there simply is not enough evidence to make a valid decision as to why the employee(s) were not abideing by an organizations operational requirements. The only thing that is obvious is that most employees understand the relationship between their employment and unemployment. Few employees would therefore desire to cause harm to that relationship to the point it no longer exists, especially in times when jobs are difficult to find. Operating from that assumption one would need investigate both sides of the equation so the issue might be fully understood and therefore resolved. I would assume each situation related to the statement "how to deal with employees who fail to follow work instructions would most certainly require a case by case investigation as to the underlying circumstances.
Here are some pointers
1) Don't assume the work instruction is an accurate point of process control.... ever
2) Ask the employee or employees .... these are people who perform the task each and every day ..... therefore they are the experts of the process
3) Question how the employee or employees were trained ... many times I discover they are trained by another operator and they never actually see the work instruction related to their tasks.
4) Observe the employee(s) performing the work task and write a simple process flow diagram of what they are doing then Determine if there exist any product or service failures which can be directly attributed to the how the employee is performing the tasks opposed to the written work instructions.
If there are no product or service failures occurring as a result of how the employee is performing the work task, then the whole situation is probably is simply an inept manager or technical person who assumes (incorrectly) their work to exemplary and finite which is obviously not the case. Suck it up you engineers an managers, you don't know everything, accept a few shots from the employees every now an again especially when it comes to some non value add tool such as a work instruction, you won't believe how much ground you can gain with employees by actually being human.
If there are product or service failures which are directly attributable to how the employee performs a work task. Then attempt to determine with the employee why they are performing the work in such a manner (what is the benefit to the employee?), What I often find in such situations is that employees assume they are performing work tasks faster if they attempt to stage work ahead (not focused upon or don't understand lean principals). In this case its important to teach employees lean principals and why the focus on one at a time is important.
A failure I discover among most employees and a failure I attribute to Management, is the fact it never trains its employees concerning the financial process of the organization. Every employee in an organization should be able to understand the organizations P&L and be fully familar with financial concepts such as assets (both liquid and illiquid) , gross profit, net profit, losses, and profit margins. Employees should be able to watch a presentation on the organizations P&L statement and understand generally what is being discussed. Employees with this level of financial understanding can not only improve the organizations bottom line, they can improve their own financial situation, making themselves and their families more secure.
The final two cases are HR cases
The first is a disruptor who will do things just to challenge management. These are usually people affected by outside situations, such as change, or political or religious ideological subversion, or some type of addiction problem. People who have been ideologically subverted are both unreasonable and irrational and will not listen to reason, in most cases. Its best to either get mental assistance for such folks or cut ties with them completely, for the benefit of all the other employees in the organization.
People struggling with addiction can be helped with outside mental health programs, however no kid gloves for these folks they need to be fully aware the addiction in the work place will not be tolerated. The batting average for successfully dealing with addiction is unfortunately not very high
People who are struggling with change related to their job can be helped through such situations with education and positive reinforcement and lots and lots of patience.... Generally, properly handling this situation (change) produces very effective employees.
The second case is related to people who are an ill fit the position they are attempting to fulfull ..... its easy to forget in today's world that not all people are born with the ability to understand every subject. For this reason its easy to wind up with people who are a mismatch to the work they are attempting to perform. I observe this phenomenon often in manufacturing, where common opinion is that any warm body can perform manufacturing shop floor tasks however, nothing could be further from the truth. Ill fit individuals are usually the most miserable employees in an organization. Where they might make a poor employee in one aspect they might be of value in other tasks the organization needs performed. Keeping these employees in their current situation however is a detriment to the business and the employee. Maybe the organizations HR function can assist such employees in finding a position elsewhere which is a much better fit to the skills sets, understanding, and abilities the employee possess
These are some common methods for dealing with employees who don't follow work instructions (or any other employment rule for that mater)