CM, CMK

CM (Critical Machine Capability)

CM expresses the ability of the machine to produce outputs within specified tolerances regardless of deviations from the mean value. It is calculated as the ratio of the difference between the upper and lower tolerances to the width of the control limit. The CM value should ideally exceed 1.33, indicating that the machine is capable of meeting requirements with a high degree of confidence.

CMK (Critical Machine Capability Index)

CMK adds CM to take into account the deviation from the mean value. It evaluates the overall capacity of the machine to meet the requirements with respect to process variability. It is calculated as the ratio of the control limit width to the tolerance specified by the customer. The ideal CMK value is above 1.33, confirming the high capability of the machine to meet requirements with minimum variability.

Interpretation of values CM a CMK

• CM:
  • CM < 1: The machine is unable to meet the requirements and modification is required.
  • 1 ≤ CM ≤ 1,33: The machine meets the requirements, but with a low degree of certainty. It is recommended to improve the stability of the process.
  • CM > 1,33: The machine is able to meet the requirements with a high degree of certainty.
• CMK:
  • CMK < 1: The machine is unable to meet the requirements and modification is required.
  • 1 ≤ CMK ≤ 1,33: The machine meets the requirements, but with a low degree of certainty and process variability. It is recommended to improve the process stability.
  • CMK > 1,33: The machine is highly capable of meeting the requirements with minimum variability.

CM a CMK

In practice, we encounter a variety of machines and devices that produce outputs such as components, products, services and information. An important aspect is that these outputs meet specified quality requirements and comply with specified tolerances.

CM (Critical Machine Capability) and CMK (Critical Machine Capability Index) are two metrics used to assess a machine’s ability to deliver the desired results. By implementing methods to improve CM and CMK, companies move towards more efficient operations and continuous improvement.

Importance of CM and CMK

Machine capability and machine capability index are important indicators that companies should consider when:

• Purchase of new machinery and equipment
• Setting up and optimising processes
• Quality control of products and services
• Improving efficiency and productivity
• Downsizing

Practical use of CM and CMK

CM and CMK are not just theoretical indicators, but have significant practical applications in a variety of industries:

1. Production:

• Component Quality Control: CM and CMK are used to evaluate the ability of production lines and machines to produce parts that meet the required tolerances. This helps prevent scrap and rework, saving time, materials and money.
• Setting machine parameters: machine parameters such as speed, temperature or pressure can be optimized based on CM and CMK analysis. This results in more stable operation and minimises the risk of producing defective products.
• Supplier monitoring: when purchasing from suppliers, CM and CMK can be used to verify the ability of their machines to produce parts that meet specifications. This leads to better quality control of the components supplied.

2. food industry:

• Controlling the consistency and weight of products:CM and CMK help to maintain consistent food quality, such as the grammage of yoghurt or the thickness of cheese slices. This ensures regulatory compliance and customer satisfaction.
• Minimising waste material: If the CM and CMK of the filling machines is low, there is higher filling variability, leading to food waste. Improving CM and CMK minimizes waste and saves costs.

3. Healthcare:

• Control of drug dosing: CM and CMK can be applied to the analysis of drug dosing machines to ensure the accurate and safe administration of drugs to patients.
• Maintenance of medical devices: the CM and CMK values help in planning the maintenance of medical devices. If a drop in CM or CMK is detected, it may indicate the need for calibration or repair of the device.

4. Logistics and transport:

• Weighing accuracy: in logistics centres, CM and CMK can be used to check the operability of weighing equipment, thus ensuring the correct accounting of transport costs and avoiding disputes with clients.
• Vehicle maintenance: analysis of CM and CMK data from on-board vehicle computers can help identify maintenance needs and troubleshoot failures during operation.

Overall, CM and CMK are versatile indicators usable in a variety of industries. By implementing them, companies gain a valuable tool.