With the rising demand for automobiles, railways, renewables, and many other sectors, numerous manufacturers within India’s burgeoning gear manufacturing industry are investing in CNC machines, better hobbing tools, and automation. Everything seems to be functioning well on the surface: output is steady, shifts are filled, and machines are running. But the reasons for lacklustre productivity figures are not difficult to find.
The invisibles, those little, often unnoticed manufacturing inefficiencies (scrap, minor stoppages, late tool changes, cautious feeds, etc.) that gradually erode efficiencies without generating red flags, may provide the answers. While these may not affect a typical daily report, which is often focused on profit in terms of sales and numbers, collectively, the number of small stoppages, late tool changes, cautious feeds, and wasted energy often leads to hours of valuable machine time.
In this blog, we will examine the hidden factory within many Indian gear shops, where cutting time, not just gears, has become the new challenge. More importantly, how do manufacturers get the hours back to remain competitive in a price-sensitive marketplace?
The Concept of Invisible Production Losses
Invisible production losses are efficiencies that occurred because of day-to-day operational problems that cause slowdowns in production, with no stoppage or impediment denoting slowed productivity. These losses can be identified as minor misalignments leading to rework or quality problems, conservative tool settings leading to lower cutting rates, minor stops during loading, and unwitnessed tool wear.
These types of losses are less commonly noticed in gear-cutting shops compared to unplanned downtime, which is easy to track. The invisible production losses can be measured in lost minutes (or lost hours) consumed and wasted throughout each shift instead of stoppages or alarms. Wars high-precision gear manufacturing activity in India using batch-based methods for an evidently bewildering diversity of gear types; it is an everyday occurrence that such production is lost and undetected. Instead of being evidently signalled on either visual surface (e.g., monitors), spectacular gaps in productivity build over time, increasing per-part manufacture times and decreasing delivery (=timeliness of delivery).
“Most gear shops lose more time from tool inefficiencies than from machine breakdowns. But no one talks about it.”
Types of Invisible Losses in Gear Manufacturing
Small inefficiencies across shifts are often the cause of invisible production losses in gear manufacturing. The following are some of the losses of the “16 Big Losses” framework and how specifically they show up in gear-cutting operations:
A. Idling and Microstoppages in between operations
Even though they might not seem like much, quick stops during chip removal, tool adjustment, or gear blank loading add up. Idle spindles can be caused by misaligned blanks or chip buildup on fixtures, even when the machine seems to be “running.”
B. Losses from Tool Change
Avoidable downtime is caused by frequent tool changes, especially when insert wear is not accurately estimated. Many stores don’t have real-time insert wear tracking, which leads to unplanned failures or early changes that waste cycle time.
C. Slower cutting rates
Operators often run machines at safe speeds and feeds due to the fear & prevention of tool damage. This leads to longer cycle times and wasteful energy use in hobbing or shaping operations.
D. Rework and Quality Losses
Uneven chamfers or slightly misprofiled teeth are examples of defects that might not be apparent right away. Later identification of these parts necessitates reworking them, which lowers machine availability without being documented as downtime.
E. Time for Setup and Adjustment
Regular product changes necessitate recalibration and retooling, especially in batch production. Over the course of a month, even a 10-minute setup that is done multiple times a day could lead to hours of hidden loss.
Gear-Cutting Forces and Energy Waste
According to a recent study published in MDPI, it states that chip removal only constitutes around 15% of the energy consumed in gear-cutting processes, while the other 85% is waste caused by inefficient energy transfer, insufficient tool contact, distorted cutting forces, and vibration.
In general, high energy and high temperature machining like hobbing, shaping, and broaching are inefficient; however, selecting the wrong tool or inadequately optimising the tool path further hinders the efficiency. The finished gear may be dimensionally correct, but the amount of machine time and energy expended during the operation clearly indicates otherwise.
This simple fact presents an important issue for the gear manufacturer: production efficiency does not equate to apparent quality. Energy waste and cutting-time waste are in plain sight, and an optimal gear tooth may not be representative of an efficient cutting process.
Impact on Overall Equipment Effectiveness (OEE)
The overlooked production losses are one of the major influences on the areas of OEE availability, performance, and quality not captured by a traditional report. If cutting rates are lowered to protect worn tooling or if micro stoppages while part clamping are omitted, an apparent 92% uptime within a gear-cutting line might still be inefficient.
Let’s consider the following example: if you process 800 blanks per shift, then a seemingly trivial 10 seconds per blank in delay is still over two hours of machine time lost, representing almost 25% of a shift. These “stealth” inefficiencies creep into a facility, reducing productivity and capacity, leaving one with the impression that the OEE measure is healthy when, in fact, performance is actually slipping.
Beyond Parts Per Hour: Rethinking the KPI
If a high parts-per-hour indicator obscures true inefficiencies, it can be misleading. Productivity in gear manufacturing rightfully includes the efficiency at which every gear is produced, instead of just the quantity of gears produced. For the sake of clarity, a few more examples of noteworthy metrics in gear manufacturing are tool life per batch, net machining time per gear (not idle or setup), and energy use per gear.
Often, the process of “cutting gears” as a company shifts the focus towards “cutting time,” potentially causing wasted minutes as they push output while inevitably losing valuable time from tool drag, idle strokes, or feeds at par with an advancement.
The actual view of shop floor performance occurs when emphasis shifts to these far deeper metrics.
Conclusion
Gear manufacturers cannot merely focus on productivity in today’s highly competitive production landscape. That most often results in higher costs, with part quality and machine reliability forfeited for hidden costs, including smaller tool wear, minor rework, and slower setup processes. Over an extended period, minor inefficiencies add up to reduced output capacity, ultimately costing profit.
Development of a faster gear-cutting machinery type is only one part of the future; visibility is the other. In order to reveal true performance, it is necessary to be aware of where every minute and incurred kilowatt is going. And finally, what cannot be seen immediately on the dashboard and in front of your eye is measured and revealed through the initial process of cutting gears.
