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CNC machining is a subtractive manufacturing method. It uses pre-programmed computer software to relay a toolpath which tells a machine how and where to extract material from a block of material. The extraction is undertaken by motorised cutting tools.
For a full overview of CNC machining including what it is and how it works, the benefits and limitations, choosing materials and design parts for machining, see our CNC Machining Guide.
There are several benefits of CNC machining custom enclosures, the main ones outlined here.
Where tight tolerances are required, CNC machining can be very effective. The use of CAD results in extremely high accuracy parts.
A general machine tolerance of +/-0.1mm geometric tolerance is usually easily achieved with a surface finish of 1.6µm (micrometer) but tolerances tighter than 0.01µm can be accomplished where required.
CNC machining is suitable for prototypes, one-offs and small to large batch production although most cost-effective on small to medium runs.
There are significantly fewer upfront costs associated with CNC machining than there are with 3D printing and injection moulding.
There are also several ways that you can cut costs when machining an enclosure including:
The process of CNC machining an enclosure or batch of enclosures is reasonably quick. The set-up time is famously fast compared to other manufacturing methods. It is also easily repeatable; once the design is created, it can be accurately repeated.
It is worth noting that lead times may vary according to the popularity of your chosen CNC machined parts supplier. Sought after companies will invariably have longer lead times so it&#;s worth factoring this into your process where possible.
There&#;s a reason why CNC machining is sometimes called &#;precision machining&#;. It is a precise manufacturing method and is associated with exceptional quality and excellent physical properties.
Where high performance is required for your enclosure, CNC machining may be an obvious choice.
Whether you want to manufacture your enclosure in metals such as aluminium or stainless steel or an engineering plastic, CNC machining offers the broadest range of material options.
This means you can select the most appropriate material for their desired properties and cost with few limitations which cannot be said for other manufacturing methods. More information about material options can be found below.
Enclosures can be machined in a range of materials, namely aluminium, stainless steel and engineering plastics.
Aluminium is the most popular choice when it comes to CNC machining enclosures because it&#;s lightweight, the raw material is comparatively low cost and it&#;s available in a broad range of sizes.
Add to this that it is highly machinable; it generally has shorter run times due to the high rate of material removal and tight tolerances are easily achieved.
Tip: A high quality finish can easily be achieved with aluminium and finished with anodising.
You may wish to use stainless steel for your machined enclosure where certain properties are required. For example, if your enclosure is going to be used in a harsh environment or come into contact with chemicals, stainless steel may be a more obvious choice.
Tip: We recommend stainless steel grades 304 and 316 to our customers for their balance between corrosion resistance and value for money.
Plastic is often chosen for enclosures that need to be lightweight and it can be a cost-effective choice.
If plastic is desired, sometimes it is suitable to choose an off the shelf moulded enclosures and then modify it to your specific requirements with machining.
The two most common grades of engineering plastics for CNC machined enclosures are Acetal, such as Delrin®, and ABS (Acrylonitrile Butadiene Styrene).
Designers should carefully consider the tolerances of their enclosure design. Where more open tolerances are suitable, it is recommended to state this on the drawing as this can reduce machining time and therefore cost.
It may be that there are some areas of the design where a tight tolerance is critical to the function and others where fit and tolerance can be relaxed.
Another important consideration on your enclosure drawing is surface finish. Often the inside of an enclosure is not &#;customer facing&#; and therefore the surface finish could be relaxed to Ra3.2µm or greater. This will reduce time on the machine and ultimately reduce unit cost.
Specifying as a large a corner radius as possible will allow a machinist to use a larger, standard, off the shelf cutter which will save time as well as costs on specialist cutters.
Generally, to get the maximum strength from a tapped hole, the thread depth needs to be 2.5 x Ø. For example, an M3 x 0.5mm pitch tapped hole needs a maximum thread depth of 7.5mm (3x2.5mm).
Going longer than this will not bring any additional strength, but it will add cost through custom tooling requirements.
Similarly, the location of features such as PCB upstands, islands or bosses within enclosures should be considered with tooling in mind. Siting such features close to the wall of your enclosure design will make it much more complex to machine. Grouping these features together can be the most efficient design for machining.
Our blog Electronic Enclosure Design for Machining in contains a comprehensive rundown of our expert tips and advice when it comes to designing enclosure for CNC machining.
If you are looking for more details, kindly visit overmoulding services.
Every manufacturing and molding process is built on the use of tools, often known as machine tooling. Tooling refers to building various different kinds of equipment and gear required for production, such as molds, jigs and fixtures. Effective tooling allows the production of high-quality products, which also increases product life cycles, and ensures the correct functionality of manufactured goods.
Tooling is the process of acquiring, obtaining, or even manufacturing the manufacturing components, machines, and equipment needed for production. However, the tooling process varies from type to type, and no one size fits all when it comes to tooling. For example, even though they're related, urethane molding and injection molding require different tooling processes.
Understanding which tooling method is most appropriate for a particular item is essential to producing a reliable, high-quality product. In this article, we'll talk about tooling, different types of tooling, and tooling costs.
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Why Is Tooling Important?
Tooling can significantly affect the manufacturing process and the quality of the finished part. Every mass-produced component, part, or product, is made using tooling, so the effectiveness of the production chains can be greatly impacted by the quality, price, and lead time of the tooling process. Manufacturing processes can be accelerated and made more cost-effective with well-designed and well-manufactured tooling. Adequate tooling also decreases downtime due to repairs and maintenance, increases consistency, and reproducibility.
Naturally, this affects the quality of the finished product because the imperfections and ineffectiveness of the finished product might stem from improper tooling. Typically, final products and other parts must adhere to a tolerance. They might also be flawed in a way that causes rapid breakage or degradation.
A tool's inability to consistently reach the appropriate tolerances or its ability to introduce flaws into a finished product can have a significant impact on manufacturing cycles. Failure of the tooling can, in the worst situations, result in production snags, downtime, and even product recall.
What Are the Different Types of Tooling?
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There are three basic types of tooling in manufacturing, ranging from product development to the beginning of the production process and mass production runs.
Soft Tooling
Soft tooling, often referred to as prototype tooling, is an efficient tooling technique used for urethane molding, which enables manufacturers and product developers to quickly make low to medium part volumes &#; usually during product development. The most popular soft tool material for cast urethane is silicone, and using this material in low-volume production runs, and prototyping is perfect.
Soft tooling is also the recommended technique for producing intricate mold patterns that would otherwise take too much time to make. However, it also has some restrictions. Soft tool materials frequently lack the sturdiness or wear-resistance of tools made with hard tooling because, as their name suggests, they must be soft.
For instance, silicone tools are likely to only be able to produce 25 components before they need to be replaced. Changing soft tools after tooling is finished is also challenging. An alternative to soft tooling using silicone is 3D printing &#; an equally efficient but less-cost effective method of soft tooling.
Bridge Tooling
Bridge tooling, or rapid tooling, is a molding technique used in the interim between product development and manufacturing. Prototypes are frequently approved, and production tooling begins immediately, but the traditional manufacturing of hard tooling &#; using steels &#; is a very time-consuming procedure.
This is a problem for manufacturers facing a very high demand with a very scarce supply. To close the supply gap, less conventional molding techniques, including silicone plastics, hard plastics, and aluminum tooling, are used to initiate production. This satisfies the immediate need while production tooling is entering operational capacity.
Aluminum isn't nearly as hard as steel, and such tooling can be manufactured in a fraction of the time on a CNC machine. The particular manufacturing process is almost identical to that of ordinary steel tooling, but given the shorter tooling manufacturing time, bridge tooling brings products to the market much faster.
Hard Tooling
Hard tooling is a method of tooling often used for injection molding. Hard tools can quickly produce large volumes of parts because they are built of sturdy metals that can resist numerous production cycles, such as steel or nickel alloys. Hard tooling is preferable to soft tooling when manufacturers have to comply with stringent tolerances, specifications, and function standards.
This kind of equipment is perfect for creating robust, precise parts. However, hard tooling is far more expensive and time-consuming than soft tooling, both in terms of up-front costs and manufacturing lead times. Using hard tooling for short production runs or only to get products to market as soon as feasible is rarely cost-effective.
Since they need additional machining, post-processing, and heat treatments to obtain a smooth finish, hard tools take longer to make. A flawless layup is ensured by a smooth finish, which is crucial for hard tools.
Injection Molds
Injection molds are the most typical type of tooling and are most commonly precision machined blocks of steel or steel alloy that serves as a negative model of the item being produced. It is essentially a two-part core and cavity that is sealed shut by hydraulic pressure. To form the item being manufactured inside the mold, a hopper full of plastic pellets is melted and pumped into the cavity under high pressure.
After cooling, the plastic component is removed from the mold by separating the two sides of the mold. The part is generally ready for assembly or post-processing once it comes out of the mold &#; this includes painting, plating, or printing. The injection molding technique almost always involves post-processing that removes bits of plastic leftover from the injection point.
Blow Molds
Blow molding is another typical kind of tooling, but it's more straightforward to make than an injection mold because it only needs a cavity and doesn't require a core. In order to manufacture a negative version of the component being produced, this kind of tool is also precisely machined from steel or steel alloy blocks. When a blow mold is being produced, its two halves come together to compress a curtain of melted, malleable plastic, trapping it inside the mold.
Air is blasted into the center of the plastic curtain as it melts, propelling it outward against the mold's walls to adopt the shape of the finished product. A small injector is also trapped between the two parts. After cooling, the item is released from the mold with a hollow interior. All kinds of bottles are made using blow molds.
Rotational Molds
Roto molds are similar to blow molds, but the "injection" method differs greatly from the previous types. With this kind of equipment, a predetermined amount of plastic pellets are placed within the mold, and the two cavities come together. Once the plastic in the mold has melted and coated the interior of the mold, it is heated and spun on various axes.
Despite the fact that the procedure is substantially longer than previous molding methods, it is a good choice for creating very big components and sections that need thicker walls. This is how some kayaks, large liquid holding tanks, and children's playground equipment are manufactured.
What Are the Costs Associated With Tooling?
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The precision and performance characteristics of a tool will determine the speed and precision of finished parts. No "lowest cost" sourcing is involved in the tooling process, as proper tooling guarantees production repeatability and the precision of every item or product that leaves the production or assembly line.
Tooling costs will depend on the type of product made. The percentage of top-line costs that go toward company tooling can be as low as 3% or as high as 6%. It's worth pointing out that tools are typically seen as consumables because all tooling eventually needs to be replaced.
For example, let's say a business produces small parts as part of its product mix and produces precision volume units for each customer. In that situation, analysis of use over time can be used to properly anticipate tooling costs.
However, let's say the business manufactures many standard parts or multiple custom items in bulk or as one-offs for each client. In that instance, they'll need to transport a larger selection of instruments to consider various factors like blank material.
There are several factors that affect the cost of tooling, and they're mostly related to the material, labor, and quality.
Material &#; High-strength component specifications are highly strict in fields like medicine, aerospace, and defense. To make cuts in materials like hardened steel, titanium, and others, you'll need even harder tools. It seems more sensible that those tools cost more than tools used for polishing, boring, or cutting softer materials.
Labor &#; The tooling cost is also influenced by how many operations the CNC machine must perform. Fewer and simpler cuts and bores require fewer tools and less action, while more intricate cuts and bores require more labor and more tools used in production. The manufactured components could also need particular surface treatments, like polishing. Costs associated with tooling will rise with each subsequent step in the design criteria.
Quality &#; Tools should be sourced from knowledgeable suppliers with a thorough understanding of the cutting surfaces' performance characteristics. To prevent quick dulling or brittleness, they must be manufactured according to precise manufacturing process standards that guarantee the right temper and heat treatment. To avoid using tools with insufficient force, speed, or capability, they should be properly matched to the equipment being utilized.
Summary
If you want to learn more about tooling and view some of our tooling products, visit Reid Supply &#; a premier provider of over 40,000 industrial components to the North American market, which maintains a partnership with over 200 leading brands. We also offer an extensive downloadable library of guides and other professional literature.
Want more information on extrusion prototype services? Feel free to contact us.