Page 54 - MetalForming April 2016

Tooling by Design
By Peter Ulintz
Four Strategies for Maintaining Dies and Equipment
In general, the types of maintenance metalformers perform on their stamping dies and pressroom equipment fall into four categories:
• Reactive
• Preventive
• Predictive
• Proactive.
Reactive maintenance is nothing
more than reacting to failed tooling or equipment by restoring its intended function. For example, when a techni- cian or quality engineer observes an unacceptable burr height on a stamped part, he summons the toolroom to replace the punch. This restores the tooling to its intended working condi- tion so that production can resume.
Many companies rely solely on this type of maintenance operation— acceptable in limited circumstances, but typically a very costly way to operate. Breakdowns become unpredictable; labor and material resources cannot be planned in advance for repairs, sort- ing of suspect parts or replacing defec- tive product maybe required; the shop may have to pay premium rates for unplanned overtime; expedited ship- ping costs may be incurred; and the shop may experience delayed down- stream processes. Most importantly,
Peter Ulintz has worked in the metal stamping and tool and die industry since 1978. His back- ground includes tool and die making, tool engi- neering, process design, engineering manage- ment and advanced product development. As an educator and technical
presenter, Peter speaks at PMA national seminars, regional roundtables, international conferences, and college and university programs. He also pro- vides onsite training and consultations to the met- alforming industry.
Peter Ulintz
Technical Director, PMA pulintz@pma.org
tooling and equipment life are not being maximized. By the time visible, audible or other events signal mainte- nance to react, the tooling or equip- ment likely has been damaged.
In summary, companies that rely on reactive maintenance generally expend more labor and material resources than those practicing pre- ventive maintenance.
Preventive maintenance (PM) con- sists of formal procedures and tasks designed to prevent unplanned break- downs, and to ensure the proper oper- ation of equipment and tooling. Shops schedule and perform PM tasks pre- determined by use of owners manuals, industry standards and guidebooks, and by evaluating environmental con- ditions, equipment criticality, impact on safety, past experience, etc.
PM tasks include changing lubri- cant; replacing consumable parts; and cleaning, adjusting, inspecting and testing tooling and equipment. In the press shop, an example of PM is replac- ing punches at a predetermined inter- val (number of hits) to help ensure pro- duction of burr-free parts.
A sound PM program keeps equip- ment running in good condition, and helps to extend the period between breakdowns. It also helps managers
plan and budget for replacement parts, and schedule the necessary work at predictable and convenient times. This translates into cost savings.
However, while a PM program pro- vides many advantages over a purely reactive program and will decrease the number and frequency of failures, it will not necessarily prevent cata- strophic failures. There also are adverse consequences of PM—over-mainte- nance, for example. Here, a shop per- forms unnecessary or ineffective main- tenance. For example, consider a PM schedule that requires changing or sharpening of punches every 50,000 hits, regardless of the condition of the punch point.
Conversely, shops may under-main- tain their equipment when following a strict PM regimen. Here, failure condi- tions may exist but remain unidentified and uncorrected in a timely manner. For example, consider stamping a material with yield strength at the high end of its acceptable limits, which requires punches to be changed more frequently than is prescribed by the PM schedule.
Predictive maintenance (PdM) improves on PM by using actual equip- ment performance data to determine when maintenance should occur.
52 MetalForming/April 2016
www.metalformingmagazine.com