Lathe Maintenance Safety

⚠What laws and standards require

• Industrial Safety and Health Regulations (Japan), Article 107 (Stopping operation during cleaning, etc.)

  When cleaning, lubricating, inspecting, repairing, or adjusting a machine (other than its cutting parts) involves danger, stop the machine. After stopping, lock the starting device and post a sign or similar so that no one else can start it. Exception: work that can only be done while running is allowed with measures such as guards over the dangerous areas

  On a lathe, cleaning, lubrication, inspection, and repair are in principle done with the machine stopped. This is the legal basis for lockout/tagout (locks and tags). US OSHA rules also require a procedure before maintenance: stop, isolate energy sources, apply locks or tags, release stored energy, and verify that the machine is de-energized. Hurco also says to use lockout/tagout when servicing inside the machine^[1][2][3][4]

• Industrial Safety and Health Regulations (Japan), Article 108 (Stopping operation during cleaning of cutting parts, etc.)

  Cleaning, inspecting, repairing, replacing, and adjusting cutting parts are done with operation stopped, with the starting device locked or signed (unless the structure makes it free of danger). When clearing chips or applying cutting fluid at a running cutting part, workers must use tools such as brushes

  Changing tool bits and inserts and cleaning around the tool post also require stop, lock, and tag as a rule. Do not clear chips with bare hands or rags^[1](1 source, for reference)

• Ordinance on Industrial Safety and Health (Japan), Articles 28 and 29 (Keeping safety devices effective)

  Employers must inspect and maintain safety devices, covers, and enclosures so that they work effectively. Workers must not remove them or disable them. When removing one temporarily, get permission beforehand and restore it immediately afterward

  Basis for the procedure when removing covers or interlocks for maintenance (permission, work, restore)^[1](1 source, for reference)

• Industrial Safety and Health Regulations (Japan), Article 101 (Prevention of hazards from prime movers, rotating shafts, etc.)

  Provide covers, enclosures, sleeves, etc. over dangerous parts such as prime movers, rotating shafts, gears, pulleys, and belts

  Always put back belt covers and change-gear covers that were removed for inspection^[1](1 source, for reference)

• Industrial Safety and Health Regulations (Japan), Article 103 (Power cut-off devices)

  Provide a power cut-off device such as a switch or clutch for each machine

  Each machine having a main power switch or breaker that can be locked is the precondition for lockout^[1](1 source, for reference)

• Industrial Safety and Health Regulations (Japan), Article 104 (Signals for starting operation)

  If starting operation could be dangerous, set a signal, designate a signaler, and have the signals given

  Signals for test runs after maintenance, and for restarting after several people have worked on inspections^[1](1 source, for reference)

• Industrial Safety and Health Regulations (Japan), Article 105 (Flying workpieces, etc.) and Article 106 (Flying cutting chips, etc.)

  If flying workpieces or chips are dangerous, provide covers or enclosures. If that is difficult, require protective equipment

  Basis for inspecting doors, windows, and chuck guards. Hurco says polycarbonate windows lose up to 10% of their impact resistance per year and recommends replacing them within 3 years^[1][3]

• Industrial Safety and Health Regulations (Japan), Article 110 (Wearing work caps, etc.)

  If hair or clothing could be caught in a powered machine, require work caps and work clothes

  Fasten cuffs, close pockets, and tuck hair into a cap (MHLW CNC lathe manual). Hardinge also requires safety glasses and safety shoes at all times^[1][5][6][7]

• Industrial Safety and Health Regulations (Japan), Article 111 (Prohibition of gloves)

  Do not allow gloves where a hand could be caught by a rotating cutting tool, as on drilling machines and chamfering machines

  The article's examples are not lathes, but the MHLW CNC lathe manual says not to wear gloves (except during setup). There is a fatal case of being caught while applying sandpaper to a rotating workpiece with a work glove on. RÖHM requires gloves and safety glasses for maintenance that handles lubricant with the chuck stopped. Think of it in terms of rotating versus stopped^{[1][5][8][9][10]}

• Industrial Safety and Health Regulations (Japan), Article 113 (Covers for protruding workpieces, etc.)

  If a workpiece protruding from a vertical lathe, turret lathe, etc. and rotating is dangerous, provide covers or enclosures

  There have been several accidents in which a long bar or pipe sticking out the back of the spindle bent under centrifugal force and hit the operator. The machine had warning labels but they were ignored, and there was no cover^[1][11][12](1 source, for reference)

• Guidelines for Comprehensive Safety Standards for Machinery (Japan; July 31, 2007, Notification Kihatsu No. 0731001)

  For maintenance and inspection, make it possible, in this order: (1) without removing guards or entering danger zones; (2) if removal or entry is necessary, with the machine stopped; (3) if that cannot be done with the machine stopped, in a dedicated operating mode (low speed, jog, etc.) (Appendix 2). It must be possible to cut off all power sources, lock them off, and safely release remaining energy (Appendix 4)

  On a lathe, in addition to locking the main power, check residual energy such as hydraulic pressure at the chuck and tailstock, air, and spindle coasting^[13][14](1 source, for reference)

• Lockout/tagout procedure

  MHLW material illustrates a method in which, after the main power is turned off, each worker applies his or her own lock to show that maintenance is in progress. OSHA requires that locks and tags be removed only by the person who applied them, and that people nearby be notified before restart

  When several people do maintenance, each person applies their own lock^[4][2]

• Accident case: electric shock during lathe repair

  A worker removed the limit switch cover with the power on and walked away. An “under repair” tag had been hung, but another person saw a burned-out indicator lamp, assumed the power was off, touched the switch, and was shocked

  A tag alone is not enough. When leaving, switch off the power and lock it. Do not judge whether power is on from an indicator lamp^[15](1 source, for reference)

• Checks after maintenance

  Hardinge requires checking, especially after maintenance, that no tools or parts are left in or around the machine. OSHA also says that before removing lockout, clear unnecessary items from the work area and check that parts are back in place

  Before restart, check for forgotten items and covers not put back^[7][2]

• Accident case: killed when caught between turret and chuck on an automatic lathe

  The front fence had no interlock, and the practice was to machine with the fence open. The emergency stop was far from the work position, and there were no procedures or training for abnormal situations

  Check that interlocks work, and write procedures for cleaning, inspection, and abnormal situations^[16](1 source, for reference)

• Accident case: sleeve caught while reaching for an oil can on an engine lathe

  While trying to oil a rotating steel bar, a worker reached for the oil can on the cross slide, caught a sleeve, and had a wrist severed. There was no set place for the oil can

  Keep lubrication tools in a safe, fixed place. Do not reach over rotating parts^[6](1 source, for reference)

• ISO 23125 (Machine tools – Safety – Turning machines) / JIS B 6031:2014 (Japan)

  Divides lathes into four groups (manual, manual with simple NC, CNC lathes and turning centers, single- and multi-spindle automatic lathes) and sets out hazards and safety requirements. JIS B 6031:2014 is identical to ISO 23125:2010 + Amendment 1:2012

  Provides the framework for checking safety functions such as interlocks and guards after maintenance. The current ISO edition is 2015, and replacement by ISO/DIS 23125-1 is under way. JIS remains at the old edition^{[17][18][19][20]}

• Values from ISO 23125 (as introduced in a chuck manufacturer's manual)

  RÖHM presents, as following ISO 23125, a rule that movements leaving a gap under 25 mm risk trapping hands or feet, and that the speed of parts approaching each other must be 2 m/min or less (the same applies in adjustment and maintenance)

  A guide to the speed when moving in jog or adjustment mode during maintenance. Not checked in the ISO text itself^[10](1 source, for reference)

• ISO 14118:2017 (Safety of machinery – Prevention of unexpected start-up)

  Sets out design measures to prevent unexpected start-up caused by electrical, hydraulic, pneumatic, and other power, and by energy stored in gravity, springs, etc.

  The international standard on the design side of lockout/tagout^[21](1 source, for reference)

• Chuck safety (JIS B 6150 (Japan) and chuck manufacturers' cautions)

  Do not exceed the permissible maximum speed and permissible input. Determine the required gripping force and speed by trial cutting, and confirm before machining that the gripping force is being delivered. Use a cylinder with a lock valve and a solenoid valve circuit that keeps gripping even if power is lost

  After changing jaws, recheck speed and gripping force^{[22][23][24][25]}

• Share of occupational accidents caused by machinery (MHLW pamphlet)

  Machines account for about a quarter of casualties with 4 or more days lost and about a third of fatal accidents, and 80% of the causes were inadequate machine safety measures (2014 statistics)

  Both machine safety measures and safe use of machines are important^[26](1 source, for reference)

The legal provisions are summarized in Kezuriba's own words. Check the exact wording against the original text in e-Gov Law Search.