How the centre-lining process benefits manufacturers
Key takeaways
- Centre-lining contributes to consistent product quality as it reduces and controls product and process variability
- It offers numerous benefits, such as simplifying operations, reducing waste and improving safety
- Digital tools enhance the centre-lining process with instant access to key data and trends
Manufacturers need to ensure their products consistently meet or beat the often-changing demands of their customers. A quality product that satisfies the customer is achievable when the manufacturing process runs optimally, assisted by a process known as centre-lining. This blog discusses the centre-lining process and its benefits in a manufacturing environment.
The centre-lining process in manufacturing
Centre-lining is a methodology used in manufacturing to reduce and control product variability, contributing to consistent product quality. In addition, centre-lining increases machine efficiency and assists in stabilising a production process around a central product specification.
The repetitive four-step PDCA (Plan-Do-Check-Act) cycle enables continuous improvement of processes, products and services, and it covers the two objectives of centre-lining:
1. Plan and Do – determine the best settings for a process
2. Check and Act – ensure the best settings are always used
These two points are discussed in more detail below – see 4 steps to prepare for centre-lining.
The underlying approach in centre-lining is to Eliminate, Simplify, Standardise and Automate (ESSA) machine settings in order to streamline processes and remove inefficiencies, thereby improving Overall Equipment Effectiveness (OEE).
Standard operating procedures (SOPs) are step-by-step instructions for carrying out routine operations. They can help to reduce variability by outlining how machines are set up and operated. We suggest you visually display the SOP near the machine and then review it regularly so that it remains up to date.
Download the how-to guide Developing a customer-focused quality improvement plan for more tools and techniques to drive process and product improvement.
“Cease dependence on mass inspection. Build quality into the product from the start.”
— W. Edwards Deming
— W. Edwards Deming
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4 steps to prepare for centre-lining
The four steps involved in preparing for centre-lining are as follows:
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Identify the important process factors or variables
The key variables in your manufacturing process can be determined by operators and agreed upon by the relevant stakeholders. It’s important to select the correct variables if you truly expect to have a positive effect on the process and product quality. That’s why it’s advisable to get a subject matter expert, such as a process, technical or quality specialist, to evaluate your process and identify the variables you’ll centre-line.
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Determine the best settings and ranges for all the important variables – by grade or product if multiple products are being produced
Your next step will be to create limits for these key variables. Here, you’re basically determining the acceptable range for each variable – with upper and lower control limits – to allow for flexibility to deal with outside influences. Anything falling outside of the acceptable range will result in unacceptable product quality. The implementation of these settings will be the responsibility of asset care personnel. See graph below.
Control limits and centre line
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Determine how these variables affect the process and the product
Once your key variables and variable limits have been established, you’ll need to monitor them to evaluate your newly centre-lined process. This is where access to accurate, clearly presented data is enormously important. (Although it’s possible to evaluate a centre-lined process using manual methods of data recording, it’s time-consuming to record and recall that data, and the possibility of data error is quite high.) See How digital tools enhance the centre-lining process.
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Ensure that the centre-lined settings are always used during production
Now that you’ve figured out your optimal process, here’s where you refine your formula. Inform operators and engineers about your new processes and make resources available that allow them to easily understand any changes you’ve implemented. At this stage, you’ll want to make sure you have solid reporting on an hourly, daily or weekly basis to evaluate product quality against centre-lines.
Download the infographic 12 steps to reduce variation with centre-lining which unpacks the centre-lining process in greater detail.
Important roles and responsibilities in the centre-lining process
The operator:
- Checks centre lines at every shift
- Ensures machines are running at centre-line
- Collects centre-line data and communicates non-conformances to work team and multidisciplinary team meetings
A subject matter expert (process specialist, technical specialist, quality expert) will identify adjustable points and verify technical correctness of settings.
A centre-line process owner (department managers, process engineer, best practice leader, quality manager) will be the coach or trainer of the centre-line process and ensure that centre-lining is implemented effectively.
Maintenance personnel will make necessary enhancements to machines and assist in compiling documentation.
How digital tools enhance the centre-lining process
Data records about machine set-ups and adjustments are often stored on printed paper, which can be time-consuming to access or update. Nowadays, some forward-thinking manufacturers are using digital tools such as mobile devices or digital dashboards to retrieve and store operational data. This includes quality measurements and information about adjustments to specific machines. These digital tools can use machine learning and historical data to automatically derive adjustments.
The tools help to automate the centre-lining process, provide easily accessible information about a process, and help operators complete their task faster and more efficiently.
The benefits of centre-lining
Centre-lining offers many benefits – it:
| Improves quality: | Improves safety: |
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| Provides operational stability: | Improves reliability performance: |
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| Simplifies operation: | Improves machine operating efficiency (and the OEE measure): |
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| Improves yield and reduces waste | |
| Facilitates short interval control and problem-solving | Identifies potential problems |
A continuous process
Centre-lining is a never-ending process, and continuous work on all of the steps is needed in order to reap the most benefits.
Centre-lining alone, however, cannot achieve all of the potential benefits. The best results can only be achieved if the equipment is properly maintained and upstream processes are also centre-lined. Additionally, easy access to process data and trends from past runs can enhance centre-lining efforts by making it easy to determine where the process is, where it’s supposed to be, and where it has been historically.
Download the how-to guide Developing a visual factory to find out more about ensuring instant access to valuable data and trends.
