Staying lean and profitable has always been a challenge for aftermarket gear manufacturing. Expedited delivery demands, legacy product support, unpredictable product volumes, limited warehouse space, and the expenses associated with keeping stored parts in sellable condition can make or break an aftermarket business plan. Supply chains and scheduling are chaotic at best, machine efficiency is low, while costly (but necessary) assets often sit idle in queue, waiting for the next capable setup technician. Outsourcing doesn’t provide a reliable solution with questionable quality and unpredictable lead times, all at a substantial price. It’s companies with a penchant for smart shop scheduling who invest in key equipment that will continue to set the pace.
With an industry-wide demand for seasoned talent at an all-time high, a successful aftermarket business unit looks for solutions that marry technology with fresh green talent and bulletproof processes and procedures as a margin boosting solution to drive their business forward.
Identifying the Challenges
The biggest challenges to remaining profitable in this niche market have always been maintaining acceptable accuracy, with short lead times, and low unit costs. Manufacturing 101 says “cycle times are as fast as accuracy allows with a goal of zero scrap parts.” Well, let’s set that aside for a moment and look specifically at companies dedicated to supporting legacy products. Highly skilled labor, if you can find it, comes at a premium domestically. Outsourcing aftermarket labor to lower cost markets is an effective – albeit, currently unpopular – way to keep aftermarket margins in the black. This, however, does not address the lead time concern.
In my tenure as an international product manager, I witnessed numerous overseas aftermarket programs taking two days on average to change over lines from one part model to the next. Given their labor rates, this didn’t typically break the bank, as most of their product lines had volumes high enough to justify these batch runs. They would typically – there’s that word again – switch to a new model in one or two days and then run that same model for a week or two.
Those scenarios are great. What wasn’t so great, though, were the legacy products that they would only sell 50 to 100 of per year. Two days of setup to manufacture 50 or fewer small parts is tough on most bottom lines. These lines of assets would run for only hours before being pulled down again for a two-day changeover. While labor cost was in check, lead times were soaring and customers with down equipment were at their wits’ end. These guys would typically have a job shop on call for these situations. But again, for the job shop to be profitable, the unit cost would have to be high.
Passing the cost onto the customer may make the accountants happy but it leaves the customer (end user of the product) feeling taken advantage of, which inevitably inhibits future sales. These struggling aftermarket programs were not only losing their shirts but were simultaneously undermining their company’s “new sales” efforts. The easy answer is to add assets in a bid to gain more available machine hours, but there’s always that pesky return on investment bit to contend with. It feels like throwing good money after bad to invest in brand-new equipment and a new building, while having to maintain equipment supporting business units that are barely treading water. What’s especially frustrating is to have top-of-the-line brand-new equipment sitting idle for days while changeovers are made. Most companies decide to tread along as they always have or deal with outsourcing.
Cases for Multi-Tasking
The unsung hero here is multi-tasking. Before you skip on to the next article, hear me out. Multi-tasking is not a new concept by any stretch of the imagination, and it seems that new solutions are added daily. Many manufacturers overlook this solution to their aftermarket woes due primarily to the limitations set by early iterations. Things like sub-spindle speed restrictions, multi-axis synchronization capabilities, and low system rigidity are all items that would cause any seasoned manufacturer to run in the other direction. Machine tool manufacturers have been listening. IMTS 2016 revealed countless multi-tasking solutions that added gear skiving to their repertoire although many were “under-speced,” typically lacking sufficient stiffness and the synchronization capability necessary to efficiently machine a wide range of parts. But again, the technology marches on.
Consider a family of parts where all parts within the family share some similar geometry. One such case study involves 42 total parts with many similarities. Nineteen of these parts share a common involute spline, but all of the gear teeth are different. Some have a similar helix angle, module, or similar pitch diameters, but no two are the same. The other 23 have a larger involute spline and a different internal diameter while the geometry, again, is different.
Within this case study, one workholding solution was designed to accommodate every part. Changeover now involves removing two components (via six socket headed cap screws) and replacing them with two different components and changing the part program. All of the tools, including their offsets and tool life, are stored in the machine. As long as a tool stays in the magazine, its tool life count is maintained. This is especially useful for part family members that have lower volumes or sporadic demand.
With this, unnecessary tool sharpening or tool replacement can be completely eliminated. With the addition of an off-the-shelf touch probe and a few custom macros, changing the program can be automated to match the workpiece in the machine. Further, engineering can provide an automated true one-piece flow where bar cut material is fed into a cell containing one appropriately sized Takisawa Taiwan lathe, one Toyoda GS300 Multi-Tasking HMC, and a robot tender. A production list and blanks go into one side while finished parts come out the other. Keep in mind that this fully capable cell could fit inside the footprint of an older single purpose piece of equipment.
In this case study, one of the biggest complaints was maintaining concentricity between the shaper and the hobber. With the multi-tasking solution, the chucking diameter and back of the part were finished in a lathe, the part was then chucked in the GS300 a single time. The part was then faced, holes were drilled, part diameters were turned finished, the spline geometry was skived, the crowned gear tooth was skived, and parts were deburred. The part was finished and ready for heat treat when it came out of the multitasking machine. The number-one complaint of the customer’s manufacturing group was eliminated. There can be no concentricity concerns between the shaper and the hobber due to the single chucking strategy employed. Although it was not a concern in their previous operation, better concentricity was also realized between the turned features and the involute geometries.
Another key advantage that multi-tasking brings to the gear manufacturing aftermarket is the pointing process. For low volumes, gears that require pointing will often be set up more than once.
This next case study involved a high-production environment. However, this manufacturer’s heartburn is all too familiar to the aftermarket. Their previous process involved turning the part from cast, shaping the internal gear teeth, drilling the holes, and then pointing the gear tooth. Their biggest bottleneck was an inefficient pointing machine. This particular machine needed to probe the teeth to determine an index location before machining. It took approximately 15 seconds for the pointing machine to determine where the teeth were before any machining could start. Multi-tasking was able to alleviate this woe by skiving the internal gear teeth and pointing them in a single chucking. The geometry of the compound pointing angle relative to the internal involute geometry was more stable than they had experienced previously. I would mention that a lot of the turning and all of the holes could be machined in the same operation – tying all of the geometry back to the chucking datums.
The Benefits Abound
Consider two dramatically differing parts requiring two completely different work holding solutions. Keep in mind, a solid multi-tasking solution that incorporates all of a part’s geometry takes less time to change over than a lathe that only handles turning. With appropriate systems incorporated to check the operator’s work, you can assign one of your newest setup technicians to make countless changeovers. Some of the benefits here include less downtime making changeovers, lower demand for skilled labor, higher-accuracy parts, faster response time, significantly lower lead times, high return on investment, lower tooling cost, the list goes on and on. Ultimately, you are changing the way you do business, setting a new standard for maximized efficiency.