A bearing housing that was once spaced in aluminium for 50 years might now be made from acetal. A conveyor guide rail that used steel in the past is now made of UHMWPE. A chemical processing component that needed stainless steel in the 90s is being made from a PTFE composite these days. Not only does this material save on weight and cost, but it’s also got better corrosion resistance. At Sydney plastic machining shops you’re seeing this trend of swapping out materials, and the engineers behind it will tell you it’s the same story again and again. Machined engineering plastics often outperform metals in very specific applications. It’s not just about saving money.
Weight reduction, scrubbing corrosion from the picture altogether, eliminating the need for lubrication, getting food safety certification without needing to go through some sort of surface treatment, and basically cutting down on noise in dynamic applications are the specific performance improvements driving this trend in material substitution out in the manufacturing sector.
When Machining Makes More Sense Than Moulding
There’s an assumption that plastic parts are always injection moulded, but that just isn’t true anymore. Sure, for massive production runs where the cost of the mould can be spread out, it’s a no-brainer. For a mid-complexity part, an injection mould tool in Sydney will set you back $8,000 to $50,000 or more. That’s a huge upfront cost that only really makes sense if you’re making a heck of a lot of parts. At certain volume levels, it actually becomes cheaper to just machine the parts instead.
Certifications and Compliance for Critical Applications
Sydney’s medical device, food processing and mining sectors have all sorts of material certification requirements. That means you can only use certain grades and suppliers of precision plastics components. If you’re making medical devices, you need materials that have been certified as safe by the FDA, TGA or ISO 10993. If you’re making food contact products, you need materials that have been certified as food-safe under one of the Australian or FDA standards. In the mining sector, in certain states of Australia, you’ve got to use polymers that meet all sorts of specific safety and performance requirements.
Design Considerations for Machineable Plastic Parts
When designing parts that need to be machined from plastic, you need to think about thread engagement. If it’s not done right, you’re almost guaranteed to end up with thread stripping under load. That’s a pretty common failure mode when your engagement length just isn’t long enough to handle the torque being applied. If you want to keep costs down, then you’re going to want to stick with standard extrusion and rod sizes as much as possible. Avoid getting into complicated deep pockets that need special tooling. Be pretty wise about the tolerances you specify. They should be enough to get the job done, but not so tight that you’re paying for more than you need.
When you get a quote from a Sydney machinist who’s also got some application engineering experience under their belt, you can bet your bottom dollar they’ll be flagging all these things up in a pre-quote review. Some bods without that experience will just go ahead and machine whatever the drawing is, regardless of what it’s going to cost. They won’t bat an eyelid at the potential issues that could have been sorted out early on in the design process.
Evaluating a Sydney Plastics Machining Supplier
If you want to get a sense of whether a Sydney plastics machinist is a good bet or not, then you need to look at three main areas. Their technical capability, their quality documentation, and their application knowledge. Technical capability boils down to whether they’ve got the in-house CNC capacity to get the job done. It also includes whether they’ve got a decent range of engineering-grade materials to choose from, and whether they’ve got the right kit to handle the sort of parts they need to make. Quality documentation is all about whether they can provide the right paperwork, like material certificates and dimensional inspection reports. It also includes having a consistent process for inspecting new parts before they ship.
