12 Principles of Maintenance (Part 1: Strategy and Prevention)

Effective maintenance is a challenge, but with the right principles in place, everything becomes much simpler. A well-configured CMMS allows for a seamless transition from continuous equipment repair to thoughtful preventative maintenance . The result? Machines are fully operational whenever production needs them.

It’s worth keeping in mind how much money is at stake. In manufacturing companies, service costs range from 2% to 10% of revenue, in transportation, they can consume 24%, and in the heavy mining industry, even 20% to 50% of the entire budget. Understanding these numbers is the first step to building a stable technical department.

1. Awareness of operating costs

The money spent on service directly impacts the company’s net profit. Since we’re talking about amounts ranging from 2% to 10% of revenue in manufacturing (or even up to 50% in heavy industry), we can’t afford to guess. Therefore, it’s important to know exactly where the money is going. By tracking these expenses on an ongoing basis, we’ll be able to budget more wisely for the coming months.

2. Predominance of planned work

According to the best standards, at least 80% of all service tasks should be scheduled , and over time, it’s worth striving for even 90%. This type of work provides comfort to the team and guarantees stability throughout production. Having a reliable plan helps us avoid unnecessary stress, stressful calls from the shop floor, and costly chaos.

3. Reduction of emergency operations

Unplanned interventions always result in stress, increased costs, and the risk of further damage. Therefore, it’s crucial that emergency repairs don’t exceed 10% of all tasks performed by mechanics . This limitation forces the team to focus on continuous diagnostics and preventing faults before they even occur.

4. Resource flexibility and time reserve

Even with the best planning, machines can be unpredictable. When planning your weekly schedule , it’s always a good idea to leave a buffer— 10% to 15% of staff time reserved solely for unforeseen situations . This reserve allows you to quickly respond to a crisis without disrupting your coherent plan for the week.

5. Eliminate rework and re-interventions

It’s important to ensure every repair is done correctly the first time. According to global standards, the rework rate (i.e., the need for the mechanic to return to the same machine) should not exceed 3%, and ideally, it should be 0%. Doing the job right once and for all builds a continuous, failure-free production process .

6. Status monitoring instead of rigid deadlines

Replacing parts simply because a certain amount of time has passed is often counterproductive. Research shows that only 11% of components wear out predictably enough to warrant replacement on a scheduled basis. As many as 89% of components fail randomly , so it’s much better to diagnose their actual condition on an ongoing basis .

7. Maximize overall equipment efficiency

Efficient machine management requires measuring overall equipment effectiveness ( OEE ). Leading manufacturing plants achieve and maintain this indicator at a minimum of 85%. This result demonstrates that the machinery is operating smoothly and with optimal time utilization.

8. Rigorous control of efficiency components

To maintain a high OEE , we must maintain three key pillars. We aim to maintain process availability of at least 95% , machine efficiency of 90% , and very high quality of around 99%. Maintaining these goals reduces defects and, naturally, increases production efficiency.

9. Schedule Compliance and Time Utilization

The technical department must respect its time. It’s worth striving for a 70% completion rate of the planned schedule – this is a sign that planning is making sense. Additionally, the effective work time indicator (when the mechanic is actually repairing the equipment) should be between 50% and 60% , ensuring a healthy balance between work and necessary logistics.

10. Discipline of technical documentation circulation

Repair history is our most valuable knowledge base. It’s crucial that our accuracy in describing and closing work orders in the system exceeds 90%. Only by continually recording work do we know how much repairs cost and what breaks down most often, which in turn helps us predict future failures .

11. Control of technical expenses

A good strategy should be financially sustainable. Exemplary companies ensure that direct maintenance costs are kept to 3% of total sales. At the same time, it’s important to ensure that these expenses don’t exceed 2% of the asset’s replacement value ( RAV ), which guarantees the company’s profitability.

12. Balanced cost structure and overtime

Too much overtime signals a lack of coherent work organization . If a company functions properly in this regard, overtime in the technical department does not exceed 6%. Expenses themselves are also important – the optimal ratio is to allocate approximately 70% of the service budget to labor costs and 30% to materials and parts .

Modern tools in practice – the example of Carl Walther

Implementing all these rules may seem complicated, but an easy-to-use CMMS system comes in handy . A prime example is Carl Walther GmbH, which centralized all fault reports and scheduled maintenance tasks using this software.

Christian Baur, the plant’s maintenance manager, explicitly emphasizes that intuitive operation and quick access to data from the shop floor have allowed his team to work much more efficiently. Thanks to the digitalization of processes and the achievement of complete operational transparency, the company has significantly shortened mechanics’ response times and improved long-term machine availability. The shift to preventative maintenance is therefore a natural step, guaranteeing operational stability.