Table of Contents
The following is the detailed design for our material handling system. Two design options were pursued during MSD I and MSD II:
- swivel and/or locking casters
- air bearings
The team first pursued the design of the caster system. A prototype was designed and fabricated to gain management and operations' feedback with hands-on model.
The air bearing design is was approved at the beginning of MSD II by Dresser-Rand after an on-site demo with a scrap compressor was completed. This demo brought new information to us, such as the the ease of use, stability during lift, and shop air system capacity.
General Project Risk Assessment
Based on direction received from Dresser-Rand, RIT faculty, and our guide, the risk assessment from the systems design level has been revised to include more technical risks related to specific solution(s) chosen to pursue. Please click the link below for the latest version:
Design #1: Caster System
Prototyping, Engineering Analysis, SimulationMechanical Design
Design Risk Assessment
Design risks were identified at the preliminary design level. The goal is to resolve these risks prior to the final design review.
Detailed Design Review
Date: Friday February 15, 2013 at Dresser-Rand
- Present caster system prototype and preliminary detailed design for full scale caster system
- Gain feedback for design, materials, construction, and operator use
- Utilize feedback to finish detailed design
Design #2: Air Bearing System
System Cost Estimation
Per Dresser-Rand's request during the air pallet systems
design review on 3/22, the team prepared a cost estimate
- caster system that can support the weight of the cylinders when attached
- air pallet system
- wagon/trailer system (exists on floor today)
- machine roller system
These estimates only include the components dedicated to their respective design, none of the other required resources (paint booth, test bay, shipping dock, etc). The team recommends the air pallet system to Dresser-Rand, and will be updating these estimates based on continued research and outreach to vendors.
Fixed Slave Frame SystemAfter the systems design review on 3/22/2013, Dresser Rand suggested effort be put into detailing the Fixed system design.
Hole PatternAnalysis was done on the varying compressor frame bolt hole patterns and how to create a station that allows for all bolt hole patterns.
Minimum Required Hole Pattern
MOS Loading Scenarios
2 Throw Pattern
4 Throw Pattern
6 Throw Pattern
The range of bolt holes would require a station that prevents movement around the frame and is not ergonomic. It is recommended that the bolt hole pattern be implanted onto the floor, and incorporate removable station supports. These supports will be placed into the correct bolt holes on the floor before arrival of the compressor.
Air Pallet - Slave Frame Interface
A flat, flush surface is required between the beam and the air pallet to distribute the load properly and protect the threads of the connecting bolt. To accomplish this a "pillow block" was designed that would act as a spacer between the beam and air pallet, surrounding the protruding bolt and nut.
After the initial design it was determined that loading this system would be impractical and unsafe as it would require a worker underneath the frame to position the nuts and pillow block. The design was then modified by welding the pillow blocks to the beam and threading the through-holes, making the nuts obsolete. The design functions under the assumption that prior to testing the connection is not critical and can be held by using a bolt that only threads halfway through the block.
Detailed Design Progress Update
On 4/19/13, the team reviewed progress of the air pallet design with Dresser-Rand for feedback.
House of Quality Assessment and Preliminary Test Plans
The specifications and house of quality were assessed with the caster system design to ensure the team is meeting the customer expectations. The current status can be found below. There are no major concerns.
The file was also updated to reflect changes due to results from the air bearing demo, which leads into our second design.
See the Final Design & Recommendations page for the final test results for the air pallet system.
Air Pallet Research
Minimal information from Airfloat was required to complete our movement system designs because we will be using a custom air pallet that can be made to the requested dimensions. Our requested pallet will be 40" x 104" x 12" when the pallet is fully lifted and in contact with the frame bottom. The air pallet will require a lifting system to lift beyond the lift of the bearings that was originally considered. The Airfloat representative did mention that due to the weight of the compressors the width of the pallet may need to increase to around 50 inches. This would extend the length of the beams required for our transport system to 60 inches. This length was still ok with Dresser Rand as it is still within the maximum width of the compressor frames.
Some research was done into lifting the completed compressors for loading and shipping. One solution that was found, without using a crane as they currently use due to cost and safety concerns, was using Grey automotive lifting units with modified attachments to lift from the beams on our transport system. After the compressor was raised above the height of the truck bed the truck would then be backed underneath the compressor and the compressor would be lowered on the truck bed with the beams from our transport system still underneath. This would cause a minimal cost to Dresser Rand because they would be shipping extra material with every compressor but because we created our system with minimal manufacturing costs this loss is small.
Design #1: Caster System
Safety as a factor for the operators working on the cart is a major concern for the team and the company. We made sure the cart was designed under the assumption that it is comfortable to work on and avoids any work-related injury. First point addressed would be the reach envelope. The 95% male and 10% female horizontal reach can cover any horizontal part of the various types of compressors currently applicable to our cart design. The horizontal reach envelope chart verifies this assumption. In ergonomics, it is a rule of thumb that we design for 10% minority female and account for majority 95% male. The height of the compressor on the cart totals 1168.4 mm which is perfect for the male vertical reach envelopes but falls a little high for 10% female vertical reach. This problem indicates that shorter operators will work uncomfortably on the cart especially when there are extended hours. This is the only problem we encountered while designing the cart and is a minor issue. It can be fixed easily by adding a floor elevation where the operator is working on. The height of the cart was specifically given by the client so that it allows minimum clearance for the cylinders to be mounted between the floor and the largest compressors. Decreasing the height of the cart will not be an option in the design. Temporary floor elevation platform will be able to accommodate any vertical reach problems. In conclusion, our cart fulfills ergonomics justification.
Male horizontal reach = 731 mm
Female horizontal reach = 676 mm
10% of female = 641 mm
Height of compressor (711.2 mm) + carts (457.2 mm) = 1168.4 mm
Male vertical reach = 68.21 inches (mean) 72.6 (95%)
Female vertical reach = 63.10 inches (mean) 67.4 (95%) 59.8(10%)
Design #2: Air Bearing System
No formal work was done on the air bearing system as the final shape of the design was not determined. The team is confident this design does not provide any ergonomic issues at the conceptual phase.
Economic Analysis for Project Pursuit
Week 8 of MSD I
Dresser-Rand completed a preliminary authorization for expenditure (AFE) form in February 2013 that summarizes the purpose, time, expenses, and revenues associated with this project. These figures are considered confidential and will not be shared here.
Using engineering economic analysis methods, the projected inflows and outflows for years 2013-2016 (4 years) were compared with the initial investment in capital and expenses to understand the discounted payback period. The payback based on these flows is 1.03 years.
The calculation is based on projected increase in sales, material, and labor due to the release of the new MOS compressor product line.
Next steps would be to work with Dresser-Rand Finance to understand their discount rate and projected flows to ensure the calculation is accurate and to gain a better understanding of the project from the financial side.
Update during Week 8 of MSD II
The AFE was reviewed with a Dresser-Rand financial analyst to fully understand the risks of the projects and how the team's design factors into these costs.
The AFE is still being fleshed out and will be finalized by the end of May 2013. It was clearly stated that the project is a strategic project due to the capacity constraint of the current assembly process, which needs to be fixed to support the increase in sales and general expansion of business.
From the financial side, the project has been justified using rate of return, net present value, and payback period. They focus on projects that give them positive rate of return and net present value on a 6-year horizon, and a payback period of less than 36 months.
The major risk of this project is the the move from a mostly engineered-to-order product to a more standardized product. The marketing team has to assume a certain market response, creating projected sales and their increases over the next 4 years. Also, there will be many one-off expenses due to inefficiencies in the beginning as the flow line is implemented that are hard to estimate and take into account.
The mixed model format of the line impacts the cost structure because each product line has different profit margins. These are one the variable still being determined. As of right now, 3 other models will be produced on the line with the MOS.