Shibaura Machine Co. (formerly Toshiba Machine Co.) recently announced the launch of its UVM range of high-precision machining centres in Europe. The UVM range is already a success story in Asia, being used for many applications, including optical moulds for LED and automotive lights, moulds for smartphone and medical parts, and press moulds for die cutting.
Shibaura Machine Co. introduced the UVM range to meet its customers’ need for:
- high-precision and high-quality machining results;
- reduced machining and machine maintenance times and therefore lower costs; and
- staying ahead of their competitors.
The UVM range is designed to achieve performance levels that impress even the most demanding of customers.
This article demonstrates how the aerostatic bearing spindle and linear-motor-driven system on these machining centres enable them to deliver unique and exceptional performance.
Aerostatic bearing spindle
Although aerostatic bearing spindles are common in the field of ultra-precision mould production, most engineers imagine they prove a drawback in conventional production due to a lack of rigidity in relation to cutting force and a heavy removal rate. However, UVM machining centres feature an aerostatic bearing spindle that has been developed and manufactured in-house, so it affords the high rigidity and torque necessary to ensure high-speed rotation accuracy and stability.
The spindle achieves over 60,000 min-1 speeds and less than 0.1 μm non-repeatable runout (NRRO). This quickly leads to high efficiency processing in applications such as mirror surface machining. There are two types of typical specifications outlined below.
The high spindle speeds lead to fast feed rates, reducing machining times. Furthermore, since aerostatic bearing spindles have no metal contact, there is no friction at maximum rotation speed, meaning spindle life is practically infinite and maintenance costs are extremely low.
Linear-motor-driven system
UVM machining centres feature an X, Y and Z axes linear-motor-driven system that is supported by the FANUC automation-numerical control (FA-NC) feedback system, as this generates less heat generation than those of other brands. There is highly accurate positioning performance in both static and dynamic systems.
A linear-motor-driven system is different from a ball-screw-driven system in that it needs a high-quality, stable feedback system to achieve high-loop control gain. There are linear motors that incorporate a core (steel stud) to achieve this and there are ones that do not. UVM Machining centres have a linear-motor that features a core, thus allowing for high-accuracy operating resolution control of 0.01 μm. Conventional machines, on the other hand, have a linear motor that does not feature a core, meaning they achieve much lower operating resolution control of 0.1 μm.
The exceptional operating resolution control afforded by UVM machining centres gives them a significant advantage over conventional machines. The designed shape of the product needs to be error free to achieve a truly smooth product surface. Conventional machines can cause significant errors in the designed shape of the product and tool trace.
Applications
UVM machining centres are suitable for a range of applications, from those involving soft materials for mirror surfaces to hard materials such as tungsten carbide for abrasion-resistance moulds and die or conventional milling tools.
The UVM series offers competitive machining in the following fields.
Medical
A UVM machining centre can be used to machine micro channels in microfluidic systems for analysing blood or DNA as well as in microreactors for manufacturing metal powder at the nano level.
It can also be used for machining press moulds and punch die for tablet production. The high precision run-out of the UVM spindle produces more punches with fewer cutters.
Semiconductor
A UVM machining centre can be used to drill holes in shower plates used for cleaning silicon (Si) substrates. A crystal diamond drill and a spindle that has less runout such as the aerostatic bearing spindle are capable of machining many small-diameter holes in a shower plate.
The image shows a total of 3,452 0.4 mm holes created in an SUS410 stainless steel shower plate using just one 0.08 mm diameter drill in 138 hours. Producing these sized holes using this sized drill means a tool life expectancy of 5,000 hours.
Mould and die
A UVM machining centre can be used to machine flat-type, press moulds for die-cutting as well as optional 4th axis rotary table, roll-type die.
Shibaura Machine Co.