Assembly Process Design and Virtual Validation€¢ Using standard process times to design manual...
Transcript of Assembly Process Design and Virtual Validation€¢ Using standard process times to design manual...
© 2016 High Value Manufacturing Catapult. All rights reserved.
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
Taking Low Carbon Technologies from Prototype to Production Using Virtual and Physical Assembly Validation
Assembly Process Design and Virtual Validation
March 2016
MTC Case Study 30876-002
© 2016 High Value Manufacturing Catapult. All rights reserved.
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
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.)
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.
March 2016
Design For Assembly Analysis
Figure 1. Checking tool access
using 3D CAD
MTC Case Study 30876-002
© 2016 High Value Manufacturing Catapult. All rights reserved.
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
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.
March 2016
Figure 2. Visualisation of a single,
flexible production line with sub-
assembly stations
MTC Case Study 30876-002
© 2016 High Value Manufacturing Catapult. All rights reserved.
Assembly Process and Cell Design
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
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
be reconfigured for new tasks.
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).
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s)
Figure 3. Designing manual
assembly cells using standard
profiles and connectors
March 2016
MTC Case Study 30876-002
© 2016 High Value Manufacturing Catapult. All rights reserved.
Human Factors Assessment of
Assembly Processes
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
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
improve and fine tune the cells and their associated assembly tasks.
Figures 4. and 5. Ergonomics
software showing line of sight and
reach testing
March 2016
MTC Case Study 30876-002
© 2016 High Value Manufacturing Catapult. All rights reserved.
Physical Assembly Process Validation
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
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.
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.
March 2016
Figure 6. 3D Printed component
fixture
MTC Case Study 30876-002