Qualitative Analysis of the Risk of CNC milling Machine Using the Approach of Failure Mode Analysis and Phase Effects

In this article, different approaches of traditional risk analysis and the phase-based multi-criteria decision-making application for quality analysis of CNC milling machine are examined. The proposed framework of this article can help the system analyst and maintenance engineer with better planning by identifying and prioritizing risks.

The statistical population of this research is 25 people and consists of experts in the fields of design, production, maintenance repair, safety and quality control. In this method, five working committees with different specializations have been used. Specialists are graded according to specific characteristics including education level, age, job position and work experience. The weight of each group of working committees is determined based on the composition of the experts. First, by using the cause and effect diagram and brainstorming method, failures were identified. A questionnaire was distributed for each of the breakdowns identified from the cause and effect diagram (Fish Bone), and opinions were collected with language expressions on a 7-point Likert scale, and the breakdown situations were prioritized using the TOPSIS phase method. Also, different traditional and phase FMEA approaches were compared.

A total of 17 failure modes were identified, seven of which were evaluated as critical for the system. In the current study, the defects of the spindle connections, the failure of the axle and bed brakes, the failure of the Y-axis bearing, the failure of the control panel handrail, the failure of the C-axis, and the failure of the Hayden Hein control panel control system. The device is identified as a priority failure and the failure of the HMI control panel as a critical failure mode.

Since about 41% of the malfunctions identified in the device under study are critical, it is necessary to plan and implement preventive maintenance and repairs for them.