What is Computer Aided Manufacturing? And how is it leading the digital site revolution?

In this article, written in 2016, we discuss the exciting design and construction opportunities offered by Computer Aided Manufacturing.

With the advancement of 3D modelling and digital manufacturing we are currently experiencing a revolution in the construction process. New developments in technology and fabrication are allowing designers to offer increasingly complex and bespoke designs to meet the changing needs of the construction market.

A lot of this new technology ties into ‘building information modelling’ or BIM that is currently used across various stages of a project from initial feasibility studies through to full coordination models for site fabrication. This process allows designers to preview and analyse designs way in advance of a projects start on site where changes and clashes can cost time and money. Another bonus of this computer aided design process is that lots of key information can be extracted from these models for scheduling, quantifying and environmental analysis.

What is Computer Aided Manufacture (CAM)?

Increasingly data generated with BIM is being used to develop code to directly control and operate machining tools in a process known as ‘computer aided manufacture’ or CAM. Following the development and commercialisation of various new CAM processes we now have a whole range of manufacturing possibilities that offer interesting and exciting opportunities for design and construction that we will look at in this article.

How does CAM work?

CAM works by taking information from a computer generated drawing to create data that can guide and control the operation of an automated tool.

For example, the lines on a 2D computer drawing could be used to generate a path command for a laser to follow when cutting out a cladding panel. The programming language generated from the drawing to control the machine tool is referred to in the industry as the ‘G Code’. As CAM technology has evolved, increasingly efficient ways of getting the ‘G Code’ from the design drawings have been developed shrinking the gap between design and manufacture.

There are a huge array of automated tools and new systems that are being developed all the time. Sophisticated equipment that was once the reserve of the car and aeronautic industry is now being used for all types of construction applications particularly where off-site factory fabrication is becoming more prevalent.

An exciting development in the field of CAM is 3D printing. Using a computer controlled ‘extruder’, custom components can be rapidly produced using ‘additive’ methods where shapes are built up in layers to create complex and dynamic forms.

What are the benefits of CAM?

* Quick transition from design information to manufactured output
* Accurately repeated components manufactured to high tolerances
* Dramatically reductions in the amount of labour required on detailed work

What are the challenges?

* CAM requires a large upfront investment and skilled operators – once this is made however much less labour is required

* Well-coordinated BIM data is required to ensure the end product is exactly to spec – however having the data available to review on a computer in advance allows for clash detection and analysis

* Some site conditions can be unsuitable for complex machines, however some more robust technologies such as CNC routing are now being operated successfully from shipping containers located on site. Also increasingly more of the construction processes are being moved off-site where clean protected factory conditions allow for the production of high quality finishes.

How is CAM being used on site?

CAM systems generally fall into one of two camps: reductive and additive processes. Reductive processes cut and carve a medium to produce a desired shape, whereas additive processes use successive layers formed under computer control to create the required form.

Reductive processes are currently more common as they only require subtle modification of existing technologies to add the computer controlled element – laser cutting of metal panels and CNC routing are quite common on new builds. The real game changer is the additive systems that use extrusion and sintering based processes.

Currently additive technologies tend to be used for smaller scale early stage work however the unique possibilities these systems offer has led to the development of much larger machines that can ‘print’ entire walls and structures directly on site.

Reductive Processes

CNC Routing:

The CNC stands for Computer Numerical Control – the router is a spinning component that can be manoeuvred to cut and carve a medium into a desired shape. Unlike a more traditional jig router a CNC can produce a one off item as effectively as a repeated identical production.

Laser / Water Jet Cutting:

Similar to CNC routing, a laser or water jet is moved over a medium on a controlled path to cut or even engrave a finish. These machines when combined with BIM data can rapidly produce effects that would take engravers months to produce. We anticipate that this technology will allow a return of the complex and beautiful decoration and structurally complex work that has been absent from more rational modern schemes.

Additive Processes

Rapid Prototyping:

Use of these newer emerging technologies is now becoming increasingly common place in the earlier stages of a project where a massing model can be quickly produced using extruded layering. For a while we have been able to literally ‘print out’ a complex 3D form using a series of extruded layers.

One key potential lies in site applications – highly efficient structures could be extruded directly on site with each entirely bespoke element being driven by the BIM data. This type of construction is already being pioneered on proposals like the MX3D Bridge that uses multi-axis 3D print robots to extrude steel into a complex and graceful structure.

Why is this technology being adopted?

In the world of construction where risks such as variable sites and unpredictable weather have led to the prevalence of more predictable conservative methods why would there be a shift to embrace these pioneering technologies?

Back in 1998 in ‘Rethinking Construction’ Latham called for the construction industry to draw from car manufacturing where CAM was facilitating the drive for efficiency and speed in production. The take up of CAM from that time was until recently was relatively slow – restricting factors such as the need for large upfront investment and time consuming research provided too much of an obstacle. At the time cheap readily available skilled labour meant there was little incentive to move towards automation.

Recently specialisms like bricklaying and plastering have become increasingly scarce which is dramatically delaying how quickly we can deliver schemes using traditional building methods. This along with the huge need for speedy and efficient construction to meet market demands is making CAM much more viable.

Innovative contractors like Laing O‘Rourke are already integrating and developing CAM systems - in fact they are currently assembling components in production line style automation in their pioneering Explore facility in Worksop, UK.

What does the future hold?

* Data will be taken directly from computer models and fed to machines on-site dramatically reducing the time spent from development to construction.

* Robotics will be used increasingly off-site for rapid low labour production – as the technology becomes more robust this will start to filter to site work too.

* Increasingly complex designs will become possible as the machines can produce bespoke components as readily as repeat forms – this will open up a whole new world of possibilities for designers.

How is Chapman Taylor using Computer Aided Manufacturing:

* At Leeds Trinity, our award-winning retail scheme, 3D modelling was used to create the dynamic flowing roof form – this was then directly used in the fabrication of the roof which dramatically reduced the time required to produce some of the bespoke panels.

* We are currently testing and reviewing our façade proposals on a ‘Build to Rent’ residential scheme with a number of laser cut study models – the data for these is processed from our BIM proposals – turned into cut out ‘airfix’ style sheets for quick and easy assembly in the office.

* We are currently developing a prototype modular system that would use cross laminate timber construction. The intention is that the drawn BIM data for the module could be used to drive the CNC router machine directly allowing us to provide a wider range of modular options quickly and efficiently.

The future for construction technology looks very promising. As the way we build evolves, the spaces we can design, create and make opens up very exciting opportunities.

Glossary:

CAD – Computer Aided Design

The use of computer programmes to create two or three dimensional graphical representations of buildings.

CAM – Computer Aided Manufacture

The use of software to control machine tools and related machinery in the manufacturing of components

BIM – Building Information Modelling

The generation and management of digital representations and functional characteristics of a place.

MMC – Modern Methods of Construction

The use of innovative technology in the construction industry to improve products or processes.

G-Code – Programming Language

A language in which people tell computerized machine tools how to make something.

The ‘how’ is defined by instructions on where to move, how fast to move and what path to move.

References:

Arcadis – People and Money: https://www.arcadis.com/media/...

MX3d Bridge: http://mx3d.com/projects/bridg...