Optimization of a hot press process for bike components - C101
| Optimization of a hot press process for bike components | |
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| Case study | |
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| Document Type | Case study |
| Document Identifier | 101 |
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| Prerequisites | |
Summary[edit | edit source]
A Canadian SME manufactures the lightest high-performance carbon composite cycling components in North America using regionally sourced materials. While many other sporting goods manufacturers have relocated facilities to low labour cost regions, this bike company has committed to remain a made-in-Canada enterprise.
In the face of increasing market consolidation and competition, the company continuously seeks ways to improve design and manufacturability and turned to the Composites Research Network (CRN) for assistance with process optimization and cost reduction.
Following a systematic diagnosis, initially developed by CRN for use by engineers in the aerospace industry, CRN identified production bottlenecks. By revisiting workflow practices together, the company and CRN identified improvements that collectively doubled production rates with minimal capital investment and no performance penalty.
The company is now implementing the low-cost approach across all its product lines and, as a result, was able to expand its manufacturing facilities and create new jobs in Western Canada.
Challenge[edit | edit source]
The sporting goods market is highly competitive and fragmented. To remain successful, bike companies must keep abreast of the latest technological advances. The aim of this project was to enable the SME to achieve its growth and profitability targets by improving productivity without major capital investments.
Prerequisites[edit | edit source]
Approach[edit | edit source]
The project started with a preliminary analysis of the company’s manufacturing workflow. The goal was to identify the process step(s) with the most impact on cost when increasing production rate. In this case, the thermal transformation step was the bottleneck limiting production rate. The hot-presses used for thermal transformation to consolidate and cure the carbon-epoxy prepreg material were already running at full capacity.
This barrier could have been simply overcome by adding new hot-presses to the production line but at the cost of major capital investment. Without the option to add new expensive equipment to the thermal transformation cell, the challenge became to optimize this step and more specifically to reduce the hot-press consolidation and cure cycle time. This was first done by optimizing the hot-presses' temperature cycle and then by breaking down the thermal transformation step in two steps, including post-curing in an oven.
The optimization process described in the flowchart below required characterization of the cure kinetics of the carbon-epoxy prepreg material used, and to develop a thermo-chemical model to simulate the thermal transformation step.
Outcomes[edit | edit source]
This project resulted in a doubling of production capacity and an increased utilization of existing production equipment with no detrimental impact on product quality or structural integrity, and with minimal capital cost.
This was achieved by optimizing the thermal transformation step using material characterization techniques and simulation tools initially developed for the aerospace industry [1].
First, a series of differential scanning calorimetry (DSC) tests were performed to develop a cure kinetics model for the carbon-epoxy prepreg material used. A cure kinetics model can predict the degree of cure (DOC) of the epoxy resin as a function of time and temperature. A complete cure kinetics model is not often provided in prepreg technical data sheets (TDS) which usually contain only partial cure kinetics data. The incomplete cure kinetics information available in a TDS quite often limits the optimization of the thermal transformation step.
Second, a thermo-chemical model was created to predict the advancement of cure and optimize the thermal transformation step. The thermo-chemical model can simulate the thermal behavior of the manufacturing (MSTE) system and can predict the cure of the prepreg material. The physics-based simulations allowed for the thermal transformation step to be revisited and, ultimately, to optimize its temperature cycle. A two-step thermal transformation cell was proposed in order to reduce the cycle time of the hot-presses. The curing time in the hot-presses were shortened by adding a post-curing step using an oven. This revisited workflow effectively doubled production rate with minimal capital investment and no performance penalty.
Related pages[edit | edit source]
- Practice for troubleshooting a thermal transformation cell
- Practice for developing a thermal transformation process step
- Curing of thermosetting polymers
- Degree of cure
References
- ↑ [Ref] Fabris, Janna Noemi (2018). A Framework for Formalizing Science Based Composites Manufacturing Practice (Thesis). The University of British Columbia, Vancouver. doi:10.14288/1.0372787.CS1 maint: uses authors parameter (link)
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Welcome
Welcome to the CKN Knowledge in Practice Centre (KPC). The KPC is a resource for learning and applying scientific knowledge to the practice of composites manufacturing. As you navigate around the KPC, refer back to the information on this right-hand pane as a resource for understanding the intricacies of composites processing and why the KPC is laid out in the way that it is. The following video explains the KPC approach:
Understanding Composites Processing
The Knowledge in Practice Centre (KPC) is centered around a structured method of thinking about composite material manufacturing. From the top down, the heirarchy consists of:
- The factory
- Factory cells and/or the factory layout
- Process steps (embodied in the factory process flow) consisting of:
The way that the material, shape, tooling & consumables and equipment (abbreviated as MSTE) interact with each other during a process step is critical to the outcome of the manufacturing step, and ultimately critical to the quality of the finished part. The interactions between MSTE during a process step can be numerous and complex, but the Knowledge in Practice Centre aims to make you aware of these interactions, understand how one parameter affects another, and understand how to analyze the problem using a systems based approach. Using this approach, the factory can then be developed with a complete understanding and control of all interactions.
Interrelationship of Function, Shape, Material & Process
Design for manufacturing is critical to ensuring the producibility of a part. Trouble arises when it is considered too late or not at all in the design process. Conversely, process design (controlling the interactions between shape, material, tooling & consumables and equipment to achieve a desired outcome) must always consider the shape and material of the part. Ashby has developed and popularized the approach linking design (function) to the choice of material and shape, which influence the process selected and vice versa, as shown below:
Within the Knowledge in Practice Centre the same methodology is applied but the process is more fully defined by also explicitly calling out the equipment and tooling & consumables. Note that in common usage, a process which consists of many steps can be arbitrarily defined by just one step, e.g. "spray-up". Though convenient, this can be misleading.
Workflows
The KPC's Practice and Case Study volumes consist of three types of workflows:
- Development - Analyzing the interactions between MSTE in the process steps to make decisions on processing parameters and understanding how the process steps and factory cells fit within the factory.
- Troubleshooting - Guiding you to possible causes of processing issues affecting either cost, rate or quality and directing you to the most appropriate development workflow to improve the process
- Optimization - An expansion on the development workflows where a larger number of options are considered to achieve the best mixture of cost, rate & quality for your application.
