Pioneers in Machining Technology
The speed and agility normally associated with a 30-taper, turret-type drill-tap centre has been built into a new, BT40 (optionally HSK-A63) horizontal-spindle machining centre (HMC) manufactured by Makino, Japan. Designated a40, the 4-axis CNC, twin pallet change machine is available in the UK and Ireland through sole sales and service agent, NCMT.
The company’s technical director, Adrian Maughan, describes the kinematics of the machine as ‘ballistic’, pointing out that it is the high rate of change of axis acceleration, or jerk, which above all leads to the a40’s industry-leading speed in the 40-taper machine sector. Additionally, the inertia of the 22 kW / 91 Nm spindle is two thirds that of the spindle in the similarly sized model in Makino’s standard HMC range.
Minimisation of idle time and maximisation of productivity when the tool is in cut were the guiding principles during development of the machine. Designed for taking light cuts from non-ferrous components, it is aimed at high-volume producers and users of aluminium and zinc die castings. Axis travels are 560 x 640 x 640 mm, the rotary table has 0.001 degree indexing and maximum table load is 400 kg.
The manufacturer states that the a40 is not applicable to producing components from ferrous metals or tough alloys. It is the high power needed to cut such materials that render conventional 40-taper machines too sluggish and inefficient for tackling near-net-shape machining of light alloys.
One of the biggest drivers of per-piece production cost is the cycle time. It not only dictates the number of machines required, but also has far-reaching cost implications affecting labour, floor space, utilities and tooling. The a40 features a collection of innovative technologies designed to slash non-cutting times, for which patent applications have been filed. Various automation options are also available to reduce cost per part still further.
The machine specification includes rigid moving elements that weigh 50 per cent less than those of equivalent HMCs, spindle acceleration from zero to 12,000 rpm in under half a second, 6,000 rpm rigid tapping, and feature-to-feature traverse rates up to 60 /min in the linear axes that are 18 per cent faster than typical 40-taper machines.
Advanced motion control optimises routine milling drilling and tapping operations. Additionally, Makino’s inertia active control evaluates component, fixture and tool weights to increase axis acceleration if the load on the table is lighter.
Side-by-side comparative tests against a couple of competitive, high-speed HMCs showed cycle time savings from 10 per cent up to one-third, depending on the type of component as well as the number of operations and tools involved and the frequency of table indexing. The machine is also very precise, assisted by cooling of the spindle jacket, ballscrews and support bearings.
The a40 uses proven systems from Makino’s 1-Series horizontal machining centres. Single-piece X- and Z-axis slideway covers, central trough chip and coolant management and dual-supports for the automatic tool change (ATC) mechanism are noteworthy design features.
The a40 employs these technologies and adds further, advanced reliability using several new systems. For example, vision-type broken tool detection supports unattended operation by validating the condition of the cutting tool after each ATC in 0.1 second, seven times faster than using probe-type systems.
Dedicated cleaning nozzles wash the tool taper with filtered coolant at the time of each tool change, ensuring contamination-free tool clamping. Three-stage coolant filtration with a 20-micron hydro-cyclone eliminates coolant tank sludge common with machining non-ferrous materials, extending time between coolant system cleaning and maintenance.
A video of the Makino a40 in operation machining an aluminium casting may be viewed at the following URL: