If you need a precise, accurate prototyping technique that is also cost effective and time-efficient, there’s only one answer.

CNC (Computer Numerical Control) turning and milling delivers incredibly accurate, high quality parts with an excellent finish, and is ideal for one-off and multiple runs to be reproduced quickly and efficiently.

The real beauty of CNC is its ability to deliver accurate parts automatically and repeatedly. Once the programme commands are loaded to the machine, everything from tool changing to feed rates, speed and even the workpiece loading process is fully automated.

The result is pinpoint accuracy, consistency and quality, even on the most complex of concept models or parts. This process guide describes the advantages and applications of CNC milling and turning, and how it can play a significant role in the production of prototypes models and finished parts.

What is CNC Milling and Turning?

CNC milling and turning is a fast and cost-effective method of producing highly accurate components with a high quality finish. The consistency of CNC milling and turning is particularly useful for batch runs of multiple units.

CNC mills and lathes have programmable directions of motion called axes. Machine types include simple mills with linear and rotary movement, to lathes and more complex machines with multiple axes that can work multi-dimensionally.

Modern CNC systems in use at Prototype Projects use computer-aided design (CAD) and manufacturing (CAM) programmes to produce end-to-end component designs.

The CAD/CAM software is used to create computerised commands which are processed to the CNC machine, which then runs an automated process to carry out the required procedures. The aim is to produce a part which is an exact match of the original CAD design.

Throughout each automated step of the operation, a skilled engineer can ensure that the process is running to the exact specifications created in the original CAD/CAM programmes.

The CNC machine can then be programmed to repeat the process, allowing multiple instances of the same part to be replicated to the same specifications.

CNC Milling and Turning benefits

CNC milling and turning is the industry standard method of producing high quality components in almost all industries because of its:

• Speed – The fully automated aspect of CNC milling and turning means that production times are cut dramatically
• Accuracy – Through the use of computer CAD and CAM programming, it is possible to achieve incredible accuracy that is measured in microns
• Repeatability – Once created, the programme can be used to produce exact copies of the original prototype to precise specifications
• Quality control – The consistency of CNC milling and turning means that quality control for longer batch runs is easier to maintain
• Cost effectiveness – A programmable and repeatable system lowers the unit price of each part, making larger production runs easier to cost manage

About Prototype Projects
Prototype Projects is an expert prototyping bureau providing rapid prototyping and model making services for clients across a range of sectors.
With 30 years of experience built on a reputation for service excellence, Prototype Projects aims to help its clients build and maintain a strong competitive edge in engineering design and production.
Underpinning its commitment to excellence and service quality is an ongoing process of investment in prototyping systems, expertise and technologies.
Prototype Projects service capabilities include:

• SLA (Stereolithography)
• SLS (Selective Laser Sintering)
• FDM (Fused Deposition Modelling)
• CNC (Computer Numerical Control) Milling (4 Axis) & Turning
• Injection Moulding (Max Shot Weight – 100g PP/ 70-80g GF PA)
• Vacuum Casting
• RIM (Reaction Injection Moulding)
• CAD (Computer Aided Design)
• CAM (Computer Aided Machining)
• CAE (Computer Aided Engineering)

Contact

info@prototypeprojects.com
Tel: 01763 249760
www.prototypeprojects.com

FDM is ideal for rapid production of small quantities of durable plastic prototype parts for testing, at relatively low cost, where the model must carry the properties of the real thing without actually being the final product.

This process guide, The What, Why & How of FDM, describes the Prototype Projects approach to producing 3D FDM models that closely represent the strength, flexibility and durability properties of the final product.

What is FDM?

FDM is a prototyping process, also known as 3D printing, that commences with a CAD drawing.  The required part is built i.e. ‘printed’ onto a plate by a heated, computer-controlled print nozzle, which extrudes the ABS plastic material over multiple layers to create a profile.

Once complete, the 3D FDM model will closely represent the strength, flexibility and durability properties of the final product.

The process normally includes the formation of a support structure which can be removed by hand on completion. Further hand finishing can smooth out small surface irregularities and layer ridges for painting.

FDM Benefits

FDM prototyping is a popular choice for product designers and engineers, particularly – though not exclusively – in the automotive industry, because of its:

• Speed: FDM is ideal for rapid production of polycarbonate and ABS prototypes
• Low cost: FDM is a relatively low cost process
• Complexity: FDM is useful for producing parts with complex geometric features
• Properties: the model produced closely reflects the properties of the final product for strength, heat resistance, UV stability and water resistance
• Testing: Because of the above, FDM models are ideal for functional testing

While mechanically ideal for evaluating design and functional testing, FDM models are not suitable for assessing the eventual manufacturing potential of the part or product.

FDM Summary

 Process features

• Ideal for small runs of prototype parts for functional testing
• Short lead times – depending on complexity – from CAD to finished part, but slower than SLA
• Cost effective
• Small numbers of parts
• Complex 3D geometries

Properties

• Heat resistance
• Strength
• Rigidity
• Stability
• Surface may be ridged
• Can be hand finished for painting

Materials

• ABS
• Polycarbonates

Pre-production applications

• Functional testing

Vacuum Casting is a fast and cost-effective prototyping method for producing small numbers of highly accurate polyurethane prototype parts. Characteristics and quality are comparable to the final product e.g. for functional testing and/or marketing.

But not every supplier can produce the fine level of detail required.

Drawing on decades of experience in Vacuum and RIM casting, this informative Process Guide describes our approach. We typically keep concessions to the absolute minimum to produce a level of detail quality to satisfy any tool maker’s production tooling requirement.

What is Vacuum Casting?

Vacuum Casting is a fast and cost-effective prototyping method that is typically used to produce small numbers (usually up to 20) of highly accurate polyurethane prototype parts.

It is a slightly slower process than SLA alone because of the additional steps involved in the process, some of which are manually intensive. The time to manufacture depends on the desired characteristics of the part, with size being a key factor as this affects the curing time of the material.

Small numbers of parts are made from a single master mould, which is made using an SLA master model. The mould is made from silicone rubber, and the casting made by pouring resin into the mould in a vacuum chamber.

The result is a bubble free casting, ideal for highly accurate, functional plastic prototype parts in very fine detail which replicate patterns, dimensions, profiles and textures.

Vacuum Casting can also produce parts with varying degrees of flexibility or rigidity, in a wide range of colours and materials – as well clear parts.

Vacuum Casting Benefits

Vacuum Casting is a fast and cost-effective prototyping method for producing small numbers of highly accurate polyurethane prototype parts.

• Ideal for functional testing and/or marketing

• Cost effective
• Low volume runs
• High quality
• Fine detail and accuracy
• Range of properties can be achieved to mimic the final product
• No requirement for expensive hard tooling.

Vacuum Casting Summary

 Process features

• Ideal for small runs of highly accurate prototype parts
• Short lead times to production
• Cost effective, with no requirement for expensive tooling

Properties

• Heat resistance
• Colours and tints
• Fire retardance
• Flexibility and rigidity
• UV stability
• Range of surface finishes
• Insert options
• Water clear
• Flexible polyurethane casting resin grades range
• Range of finishes from grades of spark texture, smooth matt and satin to a high gloss finish.

Material simulations

• ABS
• POM
• Elastomers (Range: 25 – 95 Shore A)
• Nylon including Glass Filled
• Polypropylene

Pre-production applications:

• Marketing
• Functional testing
• Thermal and air flow testing
• Assembly line trials

Process Detail

1. The first step is the production of the master part using SLA (Stereolithography).
2. The master part is mounted in a casting frame and a two-part silicone rubber is cast around it to form the mould.
3. The mould cures inside a heating chamber.
4. Once the silicone mould is cured, the master part is cut out. The mould can now be used for casting.
5. The polyurethane resin to be used in the part is prepared with the required colouring agents. Once ready, the mould is sealed.
6. The resin is poured into the mould inside the vacuum chamber using a computer controlled process. The vacuum completely eliminates bubbles and air pockets producing a blemish free finish.
7. The resin part is now cured in a heating chamber.
8. Once cured, the resin part is removed from the silicone mould.
9. The feed and riser are removed, leaving an exact copy of the original.
10. The part can be painted or plated.
11. The part is hand-finished by one of our in-house model makers.

Firstly, in line with our policy of consistent investment in new machinery and technology, we are proud owners of a new Hardinge GX480 CNC Milling Machine which we acquired during the summer. This machine complements our existing CNC milling machines. This £30,000 capital investment increases our CNC capacity, allows us to respond more quickly to your requirements and adds an additional milling dimension to our prototyping service.

Secondly, hot on the heels of this capital investment, I am pleased to welcome our latest member of staff. For us, investing in skills and expertise is as important as investment in machines, so with an eye to the future we have taken on a 23 year-old Apprentice Engineer. When he starts with us on 26 September, he will continue his 4 year engineering course with a day each week at Huntingdon Regional College under the government’s Apprenticeship Scheme. Meanwhile he will provide an additional pair of hands as he learns his skills by supporting our full-time CNC engineers – providing high quality 1-off and bespoke precision parts.

It’s a great insight into what goes on inside our Prototyping Bureau. Have a look at our video to see the prototypes you order from us actually being made.

SLA is ideal for the production of prototype parts that are required fast (hence rapid prototyping) and, depending on your exact requirement, parts can typically be produced overnight for delivery next day.

This process guide describes the Prototype Projects approach to producing prototype parts using SLA.

What is SLA?

SLA is a rapid prototyping process that is typically used early in the product development process. It produces parts with a quality and surface finish that is usually very good. The range of materials that can be used allows for a range of tolerances and property resilience*.

SLA prototyping is a very cost-effective process. The comparatively low cost means that SLA models can be thrown away and designs modified prior to moving further into the higher cost stages of the production process.

* Prototype Projects is currently the only Prototyping Bureau in the UK to offer SLA parts using Accura® PEAK™ Plastic from 3D Systems. Accura Peak properties include high stiffness, moisture stability and temperature resistance, with excellent model accuracy. See the Accura Peak Datasheet

SLA Benefits

SLA is one of the most popular prototyping processes among product designers and is widely regarded as the first rapid prototyping process. It enables product designers to get their designs off the drawing board and on to the table quickly. Benefits include:

• Speed: The principle benefit. Depending on exact specifications, SLA models can be turned around overnight
• Low cost: One of the cheapest prototyping processes, allowing for disposable casts or prototype parts
• Low runs: Single parts can be produced quickly and easily
• Tight tolerances: parts can be produced to very specific requirements

In the overall product design and development cycle, SLA is a vital process for helping your get your products to market fast.

SLA Summary

Process features

• Ideal for small runs or single runs of highly accurate prototype parts
• Useful for concept or one-off presentation models and masters
• Very fast lead time; same day or overnight depending on exact requirement
• Highly cost effective

Properties

• High temperature resistance
• Moisture resistant
• Clear, white or translucent; colour finishing available
• High level of feature complexity
• Excellent surface finish
• Range of model sizes
• Lathing and drilling options
• Flexible polyurethane casting resin grades range

Material simulations

• Polypropylene
• PC
• High temperature high durability plastic
• ABS

Pre-production applications:

• Concept models
• Presentation models
• Investment castings
• Master patterns

About Prototype Projects

Prototype Projects is an expert prototyping bureau providing rapid prototyping and model making services for clients across a range of sectors.

With 30 years of experience built on a reputation for service excellence, Prototype Projects aims to help its clients build and maintain a strong competitive edge in engineering design and production.

Underpinning its commitment to excellence and service quality is an ongoing process of investment in prototyping systems, expertise and technologies.

Prototype Projects service capabilities include:

• SLA (Stereolithography)
• SLS (Selective Laser Sintering)
• FDM (Fused Deposition Modelling)
• CNC (Computer Numerical Control) Milling (4 Axis) & Turning
• Injection Moulding (Max Shot Weight – 100g PP/ 70-80g GF PA)
• Vacuum Casting
• RIM (Reaction Injection Moulding)
• CAD (Computer Aided Modelling)
• CAM (Computer Aided Machining)
• CAE (Computer Aided Engineering)

Contact

info@prototypeprojects.com
Tel: 01763 249760
www.prototypeprojects.com