Milling is one of the most popular forms of machining and belongs to the chip milling group – in the shaping process, excess material is removed in the form of chips of repeatable form and size. Such machining methods allow the manufacture of parts of various shapes and complexity levels.
Contemporary mills allow shaping a vast variety of parts 2D and 3D out of many types of material – from wood and polymers to metal alloys (eg. aluminum, steel, brass, copper). To show its full efficiency contemporary machining devices (especially numerically controlled) require dial-in good working parameters.
These parameters should be adjusted to the processed material, technique of machining, and step in the process (eg. raw shaping or finishing).
There are two key parameters in that area: climb milling and up-cut milling. Both of these are related to the direction of turning blades in relation to the machined area during feeding. Both have advantages and disadvantages and are recommended in different types of processing material.
What are these differences and how to select the right technique for the material?
What is up-cut milling?
Up-cut milling, often called 'a traditional' is a form of machining when feed direction is opposite to the direction of cutting blade revolutions. While using that technique chips are thrown in the direction of an unmachined surface in that pass of the spindle. Blades remove material 'from the bottom to the top'.
Up-cut milling technique has the following features:
- removing big amounts of chips during passes, which can create a risk of accumulation of exceed material in machined surface,
- medium to high friction and risk of increasing working temperature,
- partial crushing of machined surface (especially in areas closer to the surface) and removed hips,
- can cause a decrease in the quality of the machined surface, but only if working parameters are poorly dialed or calculated. That can lead also to damage to machining tools (eg. due to cutting blade chipping or build-up on the blade),
- in traditional milling (automatic) – due to forces direction – can cause 'tamping' machined material,
- additionally – the mentioned crushing forces can cause a hardening surface after each pass.
Up-cut milling is popular in wood machining, especially in shops that use traditional mills with manual feeders. That technique is rarely used in milling metal, mainly because of high temperatures and higher risk of damaging surfaces and tools in case of wrongly dialed parameters of work.
On the other hand – that technique finds its usage in milling heat-resistant alloys or in situations when firm mounting of the machined block is impossible.
Up-cut milling is often used in machining polymers – mainly due to the direction of chip removal. Hot chips – while falling to the machined surface – can cause a thermal deformation. Removed in the direction of the unprocessed can be removed with the excess material.
What is a climb milling?
Climb milling is the most popular type of metal machining. It is a technique where the feed rate has the same direction as the revolution of the cutting tool.
In that situation, chips are thrown 'behind' the spindle, into the machined surface which decreases the possibility of build-up on the cutting tool or tangling ships around it.
Climb milling is most often used in CNC machining, mainly due to the possibility of achieving a better quality surface.
That technique characterizes:
- lower friction and smaller crushing forces,
- machined material should be mounted firmly – any type of play can cause damage to the cutting tools and the mill itself,
- when all of the milling parameters are dialed correctly – can provide a high-quality surface finish,
- better chip removal – thrown behind the spindle, into the machined surface, decreases the possibility of damaging the cutting tool and in addition, removes heat better,
- lower play tolerances – due to forces transferred poorly balanced spindles or cutter whole mill construction should be perfectly balanced and very stable. If not, such forces can cause poor surface finish, problems with the precision of milling, and – in extreme situations – even milling station damage.
Due to the features mentioned above – especially better heat dispersion – climb milling is often used to process alloys. Provided 'natural' heat removal often can replace additional systems of the following. That makes milling metals with good temperature conductivity (eg. aluminum) simpler and way more effective. Among others – this is one of the most important reasons why CNC machining operators most often use climb milling.
What are the differences between climb milling and up-cut milling
What are climb and up-cut milling advantages and disadvantages?
These features we can divide based on the key parameters of work:
- achieved surface quality – the climb milling process leaves more bookmarks than the up-cut milling,
- the direction of the chips removal – climb milling removes chips in the direction of the machined surface; up-cut throws them into not machined surface,
- play tolerances – climb milling requires higher stiffness and better mounting of the machined material – mainly due to significant cutting forces. Up-cut milling provides wider tolerances of play and can be used to machine materials that are harder to firm mounting (eg. different than horizontal milling),
- type of machined material – climb milling is used often in metal machining (eg. steel, aluminum, brass) in conventional milling and CNC-driven processes. Up-cut milling is used almost exclusively in shaping wood, polymers, and heat-resistant metal alloys,
- ease of milling operation and heat dispersion – up-cut milling generates higher temperatures during the cutting process. The reason is related to the removed chip thickness and the direction of their removal, into an unmachined surface. That is why the climb milling application is almost exclusive to metal machining – better heat dispersion or chip removal makes that type of professing in milling machines way more efficient.
Just like in other machining parameters, the selection of the right technique of machining is a matter of an operator. While choosing the right type of processing he should take into consideration not only the direction of machining but also the tool life, selection of cutting edge, material type, and hardness of desired chip width and thickness.
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At RADMOT, we offer CNC milling services, CNC turning services, as well as many additional services, including washing, aluminum anodizing, laser marking and assembly. We have at your disposal over 80 modern machines in our machine park, all from renowned manufacturers. Download the presentation and check on which machine tools we produce CNC turned parts and CNC milled parts.
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