Root Cause Analysis – Grinding Machine Failures
Type:
Root Cause Analysis Facilitation
Client:
The manufacturer produced machined parts for the automotive industry and were experiencing a high number of spindle failures on their fine grinding machines. The spindles were expected to last 6
months before replacement but were currently lasting 1700 hours of operating time.
It was agreed to initially perform a Root Cause Analysis investigation to determine root causes of failure and identify effective solutions to extend the life of the spindles as suggested by the OEM.
The RCA was carried out onsite over a two-day period:
- Carry out ‘on the job’ informal chats with key personnel (team leader, craft person, oil technician)
- Evidence collection from OEM manuals, and spindle failure reports.
- Conversation with local spindle repairer regards recent spindle overhauls
- Develop a timeline of failures
- Agree ‘Impact Statement’
- Develop the causal factors chart (cause and effect)
- Attach evidence to causes
- Identify effective solutions to prevent reoccurrence
- Write and issue report
Due to the nature and financial impact of these spindle failures it was agreed to utilise the causal factors approach and the seven steps towards effective Defect Elimination:
- Select RCA Type – Proactive or Reactive
- Trigger Point and Risk
- Complete Impact Statement
- Develop a Timeline
- Develop the Causal Tree (5 Why or Causal Factors)
- Complete the Report
- Action Tracking
The RCA investigation was completed in 2 days and resulted in the identification of 41 causes and 8 root causes with identified solutions.
The key details from the final report are below.
Impact Statement: Premature failure of grinding machine
spindles resulting in production downtime and scrappage of parts.
Safety: Manual handling risk when spindles changed.
Reliability: MTBF = 1700 Hours.
Quality: Increase in waste due to scrapping of manufactured parts
Frequency: 15 failures.
| Cause | Solution |
| No installation procedure exists | Develop a procedure for spindle installation with a documented sheet for reference and record. |
| No daily checks | Develop and perform daily checks. Record findings. |
| No Lubrication Education | ‘Lubrication Training’ for operators who need to use oil on machinery. (‘ICML’ Level 1 training). |
| Change of coolant procedure | Verify the coolant change procedure from 3 months to 6 months to on-condition. |
| Site Lubrication Standards | Introduce a set of lubrication standards for the control, dispensing, and handling of site oils. |
| Hydraulic Oil Lubrication Issues | Carry out a lubrication audit of oil handling and dispensing processes to identify improvements. |
| Incorrect low-level settings | Establish if the low-level alarms are functional and working correctly. Are the alarms fail-safe? |
| Bent Spindle Shafts | Ensure the spindle repairer is performing shaft checks on overhauls. Replace bent shafts if damaged. |
Key Findings:
Multiple causes, both historical and operational, led to premature spindle failure. Addressing eight identified root causes with targeted solutions will reduce downtime, extend spindle life, and improve product quality.
Pro-Reliability Solutions offer Defect Elimination and Root Cause Analysis online and in-house training, plus facilitation support.
info@pro-reliabilitysolutions.com
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