For parts that have cylindrical characteristics, using a lathe may be the best solution.
Once there was nothing simpler: the round pieces were made with lathes and the others were machined with milling machines. With the advent of CNC machining centers , which allow for easy insertion of round elements, the boundary line between the two processes has begun to fade.
The situation has become even more confusing with the appearance of motorized CNC lathes : today it is possible to complete operations that until recently were the exclusive domain of the milling department using only the lathe. As a result, determining which machine is best to produce a part has become much more complicated than in the past.
Candidates for the lathe
Some pieces are obviously more suitable for the lathe. Consider, for example, the pistons of distributors or hydraulic fittings: the cylindrical symmetry of these components, combined with the complicated external geometry and complex internal details, make them permanent guests of the turning department.
Conversely, the rectangular valve body to match the lathe-machined components, with its extensive milled surfaces, detailed cavities and intersecting holes, can never be produced on a lathe, albeit a motorized one.
Here are some reasons that prompted CNC machining to reconsider the use of the lathe. The addition of CNC turning centers equipped with motorized machines (shank milling machines) to our already extensive three-axis milling service allows us to achieve better surface finishes on cylindrical elements, offering a generally lower price to customers. The lathe makes the production of parts more efficient for which our milling skills are not sufficient. If the ultimate goal is to produce small volumes, the lathe is a good choice.
Have you designed a new camera lens housing? Have you designed a revolutionary drive shaft with flat milled surfaces and threaded transverse holes to be installed on a lawn mower? Chances are very good that we can provide you with a prototype made on the lathe.
When it comes to producing parts like these, turning offers several advantages over milling. As mentioned earlier, millers are not very fond of pistons and drive shafts with high length / diameter ratios. On the other hand, making a set of candle holders for your aunt’s 60th birthday using the lathe is a breeze.
Examples of commonly used objects
If you have not yet identified the most suitable pieces for working with the lathe, think of some objects present in any home. Making a pint glass, for example, with its smooth, regular shape and a length a few times longer than the outside diameter would be easy with a lathe, but not with a machining center. A coffee cup, on the other hand, with its protruding handle and finger hole, would be impossible to make using a lathe.
Those 2 kg dumbbells that have been collecting dust in the closet for months would be very easy to make with a lathe. The large, recessed area in which the hand grasps the bar can be made through a simple groove, but the same operation would be excruciating with a milling machine.
A teacup saucer could be fabricated with either system – alternating concentric lines and curved surfaces is possible using either a milling machine or a lathe, as the operation requires nothing more than an accurate G-code and a suitable blade. That said, the use of the lathe would in all likelihood require less time and less materials.
And what about the sprayer hose nozzle? V-grooves require a special blade in a machining center, while the lathe can use the standard turning tool. The same goes for barbecue wheels, although milling those small openings that resemble alloy wheels on the front would be very complicated, if not impossible, with most lathes.
Cylindrical tin containers, salt shakers, water bottles and flower pots: these are the ideal shapes for lathes. Milk cartons and frames? Not exactly. Protolabs offers a wide choice of materials to work with, such as aluminum, brass, low carbon steel, stainless steel, alloy steel and titanium.
Capacity of the turning service
As for the dimensions, we offer pieces with diameters up to 73 mm (sometimes 74 mm depending on the geometry) for lengths of 228 mm and diameters of just 4 mm for lengths of 1.5 mm. We can manufacture sharp conical tips, provided the angle is greater than 30 degrees, but we promise nothing when it comes to prototyping ballpoint pens or straws.
As mentioned above, our new lathes also offer the milling function. They can easily make a side hole or mill a flat surface, provided that the element is parallel or perpendicular to the long axis of the piece in question. Unfortunately, we cannot make angled holes yet. The diameter of the milled holes cannot be less than 1.2 mm however, as all our lathes have the Y axis, we are able to make off-center openings and holes (within a reasonable limit).
Do you want to engrave the company name on the pieces? Adding hollow texts is more effective with milling, while the lathe offers better results for embossed texts. We can offer almost all lettering, as long as the line width and the distance between characters measure at least 0.5 mm. The small holes do not scare us and neither do the threads. In fact, we can perform radial holes up to 2 mm and axial holes from 1 mm. Likewise, we support an assortment of internal and external UNC, UNF, and metric threads.
Probably, those who have already used our CNC machining service will notice that the surfaces made on the lathe are smoother and more rounded than the milled ones. It is possible that the milled elements have visible tooling marks, but we can perform a pearl finish on the surfaces to produce a matte effect and eliminate any burrs left after machining.
As with all machined parts, the first step is to load the CAD modelin the automatic quote processing system. Our software will determine the most suitable mechanical processing method (milling or turning) for each material; however, this decision can sometimes be ignored when setting up the quote. Each process has different capabilities as regards the realization of the desired threads and elements; prices also vary from one service to another. When configuring the quote, once these factors have been considered, select the mechanical machining process that best suits your needs. If a part is not suitable for lathe in a certain material, the option will not be available in the quote.
Over the years, we have found that round pieces made from cubes or parallelepipeds can leave something to be desired. Milling the corners of a cube to extract a curved surface takes longer than turning from a bar, and creates much more material waste. Producing these parts by turning and using specially designed machines can only prove beneficial. For more information on Protolabs turning, see the process and guidelines pages or upload your part now to find out if it can benefit from the service.
Post time: 2021-08-16