Introduction
Manufacturers across North America rely on friction welding to join components with precision, consistency, and strength. The New Britain Friction Welder is a robust machine used in heavy industrial settings, but like many legacy machines, it presented safety challenges that required modern guarding solutions and electrical integration. This case study details how PowerSafe Automation engineered and implemented a turnkey safety solution that improved operator protection, maintained production efficiency, and resolved long-standing hazards around spindle motor energy, brake release functions, and pneumatic clutch/brake systems.
The Safety Challenge
During an on-site risk assessment, operators and supervisors raised concerns about unsafe conditions on the New Britain Friction Welder. Specifically:
- Brake Release Hazards – When the spindle motor was on or coasting to a stop, pressing the brake release push button at the operator station caused the chuck to rotate unexpectedly.
- Manual Override Risks – Employees could depress the manual override on the directional valve inside the rear guarded area, unintentionally engaging the chuck.
- Stored Energy Transfer – The spindle motor’s kinetic energy was transferred through a pneumatic-controlled clutch/brake pack, creating a risk of chuck rotation even without intentional operation.
Compounding these issues was the absence of up-to-date wiring diagrams and limited PLC integration of the start/stop push button circuits. Without proper safeguarding, operators faced the possibility of exposure to rotating equipment during setup, maintenance, or troubleshooting.
Engineering Review and Findings
PowerSafe Automation engineers inspected the machine and discovered that the existing Guarding Safety Relay (S.R.) still had one unused set of output contacts. This provided an opportunity to integrate safety functionality into the spindle motor starter circuit.
The spindle motor starter control wiring was identified as:
- 120 VAC Wire #204 → Motor Starter Coil → Wire #402 Neutral
By carefully rerouting wire #204 through the Guarding Safety Relay, engineers ensured the spindle motor would disengage whenever the guarding system was opened, adding an essential safety interlock.
Implemented Safety Solution
1. Guarding Safety Relay Integration
- The spindle motor starter circuit was wired in series with the Guarding Safety Relay.
- When guards were closed, the relay energized, allowing normal motor operation.
- When guards were opened, the relay de-energized, immediately cutting power to the spindle motor starter and preventing rotation hazards.
2. Auto Mode Functionality
The team validated that in Automatic Mode, the system worked as follows:
- With all controls on and guards closed, the spindle motor energized normally.
- If a guard opened, the safety relay dropped out, shutting off the spindle motor.
- Once guards closed again, the motor re-energized without requiring the start push button, ensuring seamless restart conditions for normal automatic cycles.
- Importantly, even though the motor was re-energized, no chuck rotation or welding action occurred until the Auto Cycle push buttons were deliberately pressed.
This safeguarded against unintended motion while preserving operator efficiency.
3. Manual Mode Validation
During Manual Mode testing, operators, and engineers (including project lead Jay Kuehne) confirmed that all manual functions worked safely with one exception:
- Brake Release Risk – The brake release push button could still cause chuck rotation if the spindle motor shaft had stored energy while coasting to a stop.
Although the initial brake release wiring issue was corrected, the stored energy condition remained inherent to the machine design. This was documented as a residual risk requiring operator awareness and procedural controls.
Operator and Engineering Feedback
After repair and validation, PowerSafe Automation engineers and the client agreed on the following outcomes:
- The automatic re-energizing of the spindle motor after guard closure was both acceptable and beneficial for normal operations.
- The guarding interlock effectively eliminated hazards of spindle motor engagement when guards were open.
- The brake release hazard was mitigated as much as possible through wiring changes, but stored energy during coast-down remained a risk requiring continued caution.
- Final approval was granted by plant leadership and engineering representatives, including Jay Kuehne.
Benefits of the Safety Upgrade
1. Improved Operator Protection
The spindle motor can no longer run with guards open, ensuring operators are not exposed to rotating energy during setup, maintenance, or troubleshooting.
2. Seamless Production Workflow
The solution avoided unnecessary downtime by allowing the motor to re-energize automatically when guards closed, while still requiring intentional input for machine cycles.
3. Regulatory Alignment
The solution aligned with OSHA 29 CFR 1910, ANSI B11 series, and ISO 13849-1 standards for machine guarding, functional safety, and control reliability.
4. Cost-Effective Upgrade
By utilizing existing relay contacts and carefully integrating them into the motor starter wiring, PowerSafe delivered a safety improvement without requiring a full system replacement.
5. Documented Validation
All repairs and safety logic were tested, verified, and signed off, giving plant management confidence in both compliance and long-term machine reliability.
Lessons Learned
- Legacy Machines Need Modern Safeguards – Older equipment often lacks full PLC integration or comprehensive electrical documentation. Creative but compliant solutions can still improve safety.
- Stored Energy Hazards Persist – Even after wiring corrections, kinetic energy can present risks. Operators must be trained to recognize coast-down hazards.
- Partnership with Operators Matters – Operator feedback was critical in validating both safety and workflow efficiency, ensuring the solution balanced protection with productivity.
Conclusion
This case study highlights how PowerSafe Automation provided a turnkey safety upgrade for a New Britain Friction Welder, eliminating unsafe spindle motor engagement conditions, integrating guarding relay logic, and ensuring compliance with safety standards. The project reinforced the importance of proactive risk reduction, collaboration with plant teams, and the ability to modernize legacy machines without sacrificing production efficiency.
Through this solution, PowerSafe Automation once again demonstrated its role as a trusted partner for machine safety, guarding solutions, and factory automation projects—delivering results that protect people, improve compliance, and keep manufacturing running safely.
