Lawn Mower Manufacturer Cuts Engineering Time by Half with Pro/ENGINEER

Exmark Manufacturing, a division of The Toro Company, is the leading manufacturer of professional turf-care equipment used by landscape professionals. The company’s products include Lazer Z mid-mount zero-turning radius riding mowers, Gear-Drive and Hydro-Drive walk-behind mowing units, and UltraVac spindle-driven two- and three-bag collection systems

Reinventing the wheel. In the past, Exmark engineers designed each family of lawn and turf products from scratch so there was relatively little commonality among the different stock-keeping units (SKUs). “Our three product lines had been developed over more than a decade and included similar parts that had been re-designed from scratch to accomplish the same task,” says Steve Finkner, Senior Engineering Manager at Exmark.

This duplication of effort resulted in extra costs when designing new products, maintaining existing products, product testing, manufacturing and inventory. The previous three product lines consisted of about 36 SKUs with 3,000 parts. Only about 100 parts were shared by all models, which mostly were simple items such as nuts and bolts.

“A redesign of our entire product line provided the opportunity to rationalize and improve our design practices,” says Brian York, Engineering Process Improvement Specialist at Exmark. “We decided to redesign all three families based on one Pro/ENGINEER assembly model. The model is overloaded to contain all parts for all SKUs, while using Simplified Representations to include only those components that are relevant to the particular SKU.”

Design time cut in half. The new approach strongly encourages design re-use by enabling the engineer to tell what parts are most likely to be re-used in the right orientation. Engineers base the design of new models upon the framework of previous models and use existing parts whenever possible. The result is a substantial reduction in the amount of engineering effort required to design new platforms or models. The new product lines consist of 60 models with only 1,633 total parts, of which 360 are used on nearly all models. The increase in design re-use is the main reason why the amount of time required to design a new model has been reduced to less than half of what was required in the past.

Simplified Representations are used to quickly view the affect of a design change on any SKU

The time required to maintain product configurations has also been greatly reduced. In the past, engineers at Exmark spent considerable effort analyzing the impact of a part change on the many models it may or may not have influenced. Now they can see at a glance exactly which models are affected. Furthermore, they can make a change to the part and use Simplified Representations to cycle through all of the models to see how the change affects each model. Having all the parts in one assembly allows the engineers to use the Pairs Clearance feature of Pro/ENGINEER to identify any interference between the changed part and any models on which it is used.

The reduction in the number of unique parts reduces the amount of testing that is required to about one-third the previous level. This reduction comes primarily from the reduced number of parts that require testing. For example, the number of frames has been reduced from 21 to three and new frames share a number of common subassemblies.

Major improvements in manufacturing. The increased design commonality has also improved manufacturing. “We used Simplified Reps to evaluate different assembly process alternatives,” says Jeremy Tate, Sr. Design Engineer at Exmark. “Previously, we needed four assembly lines to build 36 models and changeover from one model to another took approximately one day. Our new process builds 60 models on only two lines and changeover is nearly instantaneous. The assembly model was also used to design the weld tooling. Not to mention, the reduction in the number of unique parts assisted in a significant reduction of warehouse space.”

3D images of assembly process helps assemblers learn their jobs

“In the past it used to be impossible to keep all 36 models accurately updated to reflect the latest design changes,” Finkner concludes. “Now with only one assembly model—within the same overloaded master assembly—to update, it has become possible to ensure that accurate and complete documentation is provided for every model. The Simplified Reps feature was used to create 3D images of the parts in different stages of the assembly process that help our assemblers gain a much better understanding of their jobs. These changes, along with other factors, have contributed to a substantial reduction in warranty costs for our new lines.”

Source: PTC Express

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