MTC Case Study 30876-002
March 2016
Assembly Process Design and Virtual Validation
Taking Low Carbon Technologies from Prototype to Production Using Virtual and Physical Assembly Validation
The Proving Factory is a £22m manufacturing initiative designed to strengthen the UK’s automotive supply chain. The project, established with funding from the private sector and the government’s Advanced Manufacturing Supply Chain Initiative (AMSCI), was created to provide a route from prototype to production for advanced low carbon technologies. A key objective was to establish a flexible UK manufacturing and assembly facility capable of volume production (200,000 units/annum) for 6 high speed, rotating powertrain technologies, thereby de-risking future OEM investment. The role of the Manufacturing Technology Centre (MTC) within the project was to support Productiv in the industrialisation of the Proving Factory assembly facility concept through: •
Applying a Design For Assembly methodology to optimise the technologies for mass production
•
Simulating manufacturing systems to suggest an optimal strategy for production
•
Using standard process times to design manual and semi-automated assembly cells
•
Analysing 3D models of the assembly cells using an immersive Virtual Reality suite and ergonomics software
•
Physically validating processes through manual assembly test builds and automated pick-and-place robot trials
© 2016 High Value Manufacturing Catapult. All rights reserved.
MTC Case Study 30876-002
March 2016
The initial six technologies selected for the Proving Factory entered the project at prototype level. Their designs were focused on demonstrating the viability of each technology through small batch production. For this reason, many components were machined from billet and assembly
Design For Assembly Analysis
processes based on workshop practices.
To enable mass production of the technologies, the MTC applied a Design For Assembly (DFA) methodology with three key principles: 1. Functional Analysis – facilitates part count reduction by the evaluation of each component in the design in order to determine whether it is essential for the performance of the product. 2. Feeding Analysis - evaluates the suitability of a component for manual handling to the point of assembly 3. Fitting Analysis - is used to highlight problems and inefficient operations associated with the build sequence and component interfaces, and to identify the tooling requirements of the design
Figure 1. Checking tool access
(Figure 1.)
using 3D CAD
The assembly hierarchy for each product was mapped and each process within it analysed. Applying these techniques raised potential assembly issues early and resulted in a significant reduction in part count across the technologies. It also highlighted opportunities to commonise commodity items such as fasteners, seals and sensors.
© 2016 High Value Manufacturing Catapult. All rights reserved.
MTC Case Study 30876-002
March 2016
Assembly Strategy Review The specification for the Proving Factory assembly facility detailed a flexible facility that could produce up to 20,000 units per annum for ten different technologies.
This shared factory concept raised various
questions regarding the best way to design a factory that can deal with large variation in product whilst maximising commonality and minimising investment costs.
The MTC researched various possible strategies from several industries and highlighted two potential solutions: •
A single, flexible, mixed-model assembly line capable of assembling any product (Figure 2.)
•
Cellular manufacture, with each product assembled in a dedicated cell
Figure 2. Visualisation of a single, flexible production line with subassembly stations
Using modelling and simulation techniques, the MTC then tested the performance of each system and used the results to build a comparison matrix, which also considered factors such as training, logistics and reliability. The matrix showed cellular manufacture to be the optimum strategy, with large investment resources such as clean-rooms shared between cells.
© 2016 High Value Manufacturing Catapult. All rights reserved.
MTC Case Study 30876-002
March 2016
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Time (s)
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With a cellular manufacturing strategy signed off by the consortium, the MTC’s next task was to design suitable cells for assembling the technologies. This was achieved by creating a spreadsheet tool for mapping standard process times to each component in a given Bill Of Material. Within the tool, these processes were then divided amongst several operators to create a balanced assembly line capable of producing each product at the required rate.
The large majority of assembly processes were designed to be carried out by
Assembly Process and Cell Design
manual operators, dictated by the production volumes and degree of flexibility required. However, Process Failure Mode and Effect Analysis (PFMEA) highlighted certain procedures as high risk, for example health and safety issues with high strength magnets and also the potential for operators to damage delicate foil components. To mitigate those high risk processes a degree of automation was required. The MTC researched and compared solutions including flexible robotics, dedicated machinery and semi-automated fixtures, to compare factors such as investment and payback, commissioning and training required as well as quality. Flexible robotics emerged as the optimum solution, largely due to the ease and speed at which the systems can
Figure 3. Designing manual
be reconfigured for new tasks.
assembly cells using standard profiles and connectors
The MTC also conducted a state of the art review into manual assembly work stations and equipment. Through this research, it was found that modular extruded aluminium systems were well suited to the Proving Factory assembly processes. Using software containing a library of standard profiles and connectors, production workstations can be quickly built and configured for a given application (Figure 3).
© 2016 High Value Manufacturing Catapult. All rights reserved.
MTC Case Study 30876-002
March 2016
The use of software to simulate real world manufacturing processes is becoming increasingly popular across various industries. It has been proven to reduce product development time and cost by tackling
Human Factors Assessment of Assembly Processes
production problems early in the design cycle. The information provided by modelling and simulation allows for better decisions on issues such as investment in equipment, staff and facilities.
Virtual Manufacturing software was used by the MTC to analyse the Proving Factory assembly processes. Using Computer Aided Design (CAD) models of components and equipment, a detailed 3D model of the assembly cells was created. By programming human operator assembly procedures into ergonomics software, the MTC was able to check the assembly cells and processes for issues such as repetitive strain and over-exertion. The software provides a means of carrying out operator reach and vision tests, to ensure the cell is designed as efficiently as possible (Figures 4 and 5).
The 3D models were also evaluated in the MTC’s virtual reality suite. This facility, a connected system of computers, projectors and tracking equipment, creates an immersive 3D viewing experience in which CAD models and scan data can be assessed at full scale. Viewing the Proving Factory assembly cells in this way has highlighted further opportunities to
Figures 4. and 5. Ergonomics
improve and fine tune the cells and their associated assembly tasks.
software showing line of sight and reach testing
© 2016 High Value Manufacturing Catapult. All rights reserved.
MTC Case Study 30876-002
March 2016
The MTC’s final task was to physically validate Proving Factory assembly processes. That was achieved in two phases: •
Manual assembly trials in a representative trial assembly cell
•
Assembly automation trials using a modular, 3-axis pick and place robot
Physical Assembly Process Validation
system
During the manual assembly trials, ‘Time and Motion’ studies were used to validate previous assumptions of process times. The MTC conducted trials of Bluetooth controlled fastening tools, which can be pre-programmed with assembly procedures. By monitoring the time taken to assemble each fastener, the software was able to identify operator error and lock the tool, clearly flagging quality issues.
For the assembly automation trials, the MTC used 3D printing to manufacture robot end effectors, mock components and fixtures (Figure. 6). The flexibility and speed of this process proved to be very useful, allowing each design iteration to be quickly tested and improved. The modular Cartesian robot system, built from linear servo drives, was well suited to the size of the components in question and carried out the required processes with good repeatability.
Figure 6. 3D Printed component fixture
To conclude, the Proving Factory project provided the MTC with an excellent opportunity to apply a range of engineering tools to optimise both products and processes. By considering production issues early in the development cycle, it was possible to make changes before committed costs escalated. The MTC is now applying these techniques across various sectors to bring new products to market, in an efficient and cost effective manner.
© 2016 High Value Manufacturing Catapult. All rights reserved.
