Note: Due to NDAs limited photos, drawings, and models can be shared. The product and technology I showcase in my video is a demo-line. As much as possible has been included, if you'd like to learn more do not hesitate to reach out to me.

Project Overview:

Note: Due to NDAs limited photos, drawings, and models can be shared. As much as possible has been included, if you'd like to learn more do not hesitate to reach out to me.

Pulsing Conveyor Line:

As was mentioned under the tab "AR/Projected Work Instructions" many of the manufacturing processes at this employer are largely manual for various reasons. However at one particular manufacturing site, the work culture among production associates is shaky at best. This particular group works on a line that utilizes only gravity rollers - when an associate has completed their cycle time, they move the product into the next station. However, their work culture revolves around slacking during the first half of the shift and missing cycles times more than 50% of the time, and rushing in the second half to meet the daily throughput. Not only is this not a sustainable practice (that creates bottlenecking) but many of the units that are rushed end up with serious quality defects.

This time I was asked the question of, "How can we change this work culture and introduce automation into this manufacturing site?" The obvious answer would be to implement a continuously moving line, common in the automotive world. However due to the amount of manual welding and brazing performed on this line, this wasn't an option. Instead, I decided a pulsing conveyor line would be the best solution/answer to the question posed. As a result I was responsible for process design, outlining conveyor design constraints, creating an initial design, as well as selecting and working with an integrator to land this conveyor. As of now the line is currently being installed.

Conveyor Design:

In short, a pulsing conveyor line is a motor driven line, where all products index at the same time into the next workstation (or buffer station) once production associates at each of the workstations has pressed the work complete or by-pass button. The drawing below was created by me as the initial design for the request for quote and bidding process of selecting an integrator.

The conveyor I designed contained 14 workstations and nine buffer stations. Each work station was specced out to contain a pushbutton box with three buttons: work complete, bypass, and Andon (supervisor call). Aside from these buttons being used to execute the pulsing of a conveyor they were also tied to a stack light (see image to the right) at each workstation, allowing production associates and team leads to clearly understand the current status of each station.

My design (and of course the final product) uses a continuously moving free flow chain. What is actually actuated to index the units are pneumatic paddle stops that are released once all work complete (or bypass) buttons have been pressed.

The product, on this particular line is built upon (and shipped on) a wooden pallets that are both placed on a rotating work tray. I specced a rotating work tray to allow production associates and quality staff the ability to access all four sides of the unit at any station instead of waiting for a spur/kick out as production has previously done on the gravity rollers.

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As a result of the reusable work trays, my design (and the final product) contains three different lift/elevator units with a lower level conveyor for work tray return. The first elevator at the beginning of the line uses a four chain lift (also driven by SEW motors) to place an empty work tray from the tray return onto the workstation level. The elevator at the end of line (EOL) was a more complex design that is discussed more in the next section. In short, it separates the unit and wooden pallet from the work tray before lowering (via chain lift again) to place the empty work tray on the lower return line. The last lift is actually located roughly midway through the line. The purpose of this lift was to improve worker ergonomics as it transfers mid-production units to a lower workstation height (floor to roller height). Beyond this lift the units are built up substantially taller, lowering the floor to roller height prevents associates from over stretching/reaching.

Challenges:

There were two major challenges in the mechanical and process design of this system.

The first as mentioned earlier was how to separate the reusable work tray from the unit and pallet before passing the work tray down the return line underneath. To do this I reflected upon what I had previously worked on as my time as a maintenance engineer and knew how well a gantry/fork system worked. I created an initial model (seen to the right) that was closely followed by the integrator for the final product. When a unit, pallet and work tray enter the EOL lift, pneumatically actuated forks place themselves under the pallet. Once done the four chain lift is lowered down to the work tray return level where the work tray is handed off via SEW motor driven rollers. Once done the lift returns to a slightly higher height than it was previously so that the pallet is now on the rollers. Once there the forks are

removed by the same pneumatic pistons before the pallet and unit are moved to a staging area via the same motor driven rollers.

The second challenge was to rebalance the line in order to get all stations as close to possible to an identical takt time. Seeing the longest single process was the welding of components (takt time of 89 seconds) I set this as my overall conveyor takt time. By working with my cross functional partners in factory modelling and simulation we were able to shuffle around various processes and steps between stations using Dassault's DELMIA factory modeling software so that all stations had a takt of 89 seconds.