High-End Machining at an Affordable Price

The new Tongtai CT-350 five-axis vertical machining center from Absolute Machine Tools, Inc. (Lorain, OH) features state-of-the-art performance in a small footprint. It boasts high-end machine construction and performance at an affordable price. Its structure is a “C” frame-type machine and was designed around high level mold-type machining centers to ensure rigidity during cutting. The column of the CT-350 has a wide span, making it torsion-resistant while cutting a 5-axis part. Rigidity is enhanced by using 45 mm roller type guideways and pre-tensioned, large diameter ballscrews.

The table size is 13.78 in diameter and can handle a maximum load of 440 lb. The integrated rotary table uses the roller gear cam in both the tilt and rotation axes. The roller gear cam design provides zero backlash, high rigidity, and fast rotation speeds. The stroke on this machine is 15.75 in X-axis, 20.08 in Y-axis, and 20.08 in Z-axis. The A-axis stroke is +30 deg through -120 deg, and the C-axis stroke is 360 deg with rotation speeds of 40 rpm and 33 rpm, respectively. The CT-350 is truly high performance, with rapid feed rates of 1,418 ipm in X and Y, and 1,182 ipm in Z. A 20 hp direct-drive 15,000 rpm Big Plus 40 taper spindle with air/oil mist lubrication is standard in the CT-350, however an optional 20,000 rpm integral spindle is also available.

For enhanced productivity, the standard 24-position arm type tool changer is equipped with a roller gear cam mechanism to reduce tool change time to only two seconds. Larger 30- and 40-tool ATCs are optional. The CT350 is equipped with a FANUC OiM-F CNC control to perform 4+1-axis cutting. However, if 5-axis simultaneous cutting is necessary, a FANUC 31iM-B5, Siemens 840D or Heidenhain iTNC-640 can be installed. The CT-350 is Tongtai’s smaller 5-axis machining center with a small footprint for shops that need a 5-axis machine, but do not have the floor space for a larger machine tool.

The new Tongtai SH-4000 horizontal machining center was developed for mass production line formation and fast aluminum alloy parts machining. The new compact machine has a 35 percent smaller footprint than the previous model, allowing for maximum shop floor utilization throughput. By integrating a robot on either a floor-type motion axis rail system or overhead gantry, manufacturers are able to catapult production and streamline manpower costs. The SH-4000 is equipped with a powerful 30 hp, 15,000 rpm built-in spindle, 400 mm square table, and coolant-through the spindle. The automatic tool changer can hold 60 tools with a tool-to-tool change time of 1.4 seconds and chip-to-chip time of 2.6 seconds. The cam-type automatic pallet changer has a change time of 6.0 seconds.

The SH-4000 comes standard with linear ways for speed and with optional linear scales for achieving accuracy of ±3 µm.  Travels for X/Y/Z are 510 mm each, with rapid traverse rates of 60 m/minute on each axes, accelerating at a rate of 1.0 G. The B-axis rotary table can index at 0.001 deg with or without an encoder. Because the B-axis is made with a roller gear cam mechanism, it is much more durable than a worm gear type, guarantees higher accuracy, and is preloaded for zero backlash.

The Tongtai Flexible Manufacturing System (FMS) is recommended with this model for increased finished parts volume. The FMS consists of a loading/unloading station, stacker crane, pallet container, and Manufacturing Management System (MMS) monitoring. This system is dedicated specifically for the horizontal SH-4000 and begins at the loading/unloading station, where raw materials are initiated into the FMS, and ends as a finished part. The FMS can handle up to two loading/unloading stations per cell.

Next, the part moves on a pallet from the loading station to the stacker crane where it gets loaded and ultimately unloaded in the machine(s). The pallet container allows for temporary storage of the raw materials heading to the stacker, and finished materials from the stacker back to the unloading station, or to additional machines for finishing.  The container system in the FMS can have as many as 10 pallets, or be expanded to a maximum of 20.  A Manufacturing Management System (MMS) is used to program the FMS and monitors the movement and machining of the entire system by collecting the production information for the operator.  Tongtai’s FMS is extremely flexible and each of the cell’s stations is built to coordinate with each other.

The Tongtai Intelligent Manufacturing System (TIMS) is among the newest technologies in the machine tool industry. Developed by Tongtai and partnering with FANUC, this system includes four basic management functions for any size manufacturing facility to improve productivity, machine accurately and precisely, facilitate part production, as well as provide protection and maintenance assistance for the machine tool.

The Production Management System monitors cutting loads, pallet-changing functions, records alarm messages, and assists in troubleshooting and maintenance support. The Intelligent Management System performs motor load monitoring, machining adaptive controls for protecting tooling and ensuring cutting efficiency, and crash protection for real time detection of servo loads during feeding. Tool Management records machining dates, times, and usage for tool life tracking and management, tool compensation, and tool overload protection. The fourth management function is Workpiece Management, which incorporates software using a built-in CCD camera to monitor the characteristics of a particular workpiece, and calculates and compensates program coordinates for maximizing machining precision.

Tongtai has several different models of 5-axis machining centers. The HTT-1250 is a large horizontal machine for aerospace applications with 50 in tilt/rotary table. The GT-800 and GT-630 are gantry-type high-speed, high feed rate machines with 31.5 in and 25 in tilt/rotary tables, respectively. The MDV-551-5AX is a small, double-column-type machine with high-speed rotation and a 20 in tilt/rotary table.

Absolute Machine Tools also offers the Johnford DMC Series double-column moving table bridge mill that is created from a one-piece Meehanite® cast iron bridge/column assembly that takes up 30 percent less floor space than comparable C-frame vertical machining centers. Available in both moving table and sliding column (fixed-table) versions – ranging from 36 in x 36 in x 30 in of travel up to 60 ft x 20 ft –the bridge mills have a long base casting with complete support of the table over the full 51 in of Y-axis travel, allowing massive loads to be machined.

The Y and Z axes hold fixed loads at all times, while the X-axis carries the only dynamic load allowing for tight machining and tight tolerances during high-speed machining operations. Because there is no table overhang, X-axis pitch and yaw are eliminated. The spindle centerline-to-column distance is minimized offering further rigidity. The machine’s heavily ribbed cast iron construction provides long tool life and part surface finish. The combination of twin screw-type conveyors and a caterpillar conveyor ensures complete chip removal with little manual cleaning. Finite element analysis (FEA) is used to design each bridge mill, simulating the effects of real world conditions, including vibration, heat, fluid flow and other physical impacts.

DMC 900-1500H small-frame series bridge mills feature a fixed column with moving table, X-axis travel from 35.40 in to 59.1 in, Y-axis travel of 35.4 in, and a Z-axis travel of 30 in, and table load capacities from 6,600 lb to 13,200 lb. DMC 1600-3100H medium-frame series bridge mills offer a fixed-column construction with moving table, X-axis travel from 63 in to 161.4 in, Y-axis travel of 51.2 in, and Z-axis travel of 31.5 in, with a table load capacity of 13,200 lb.

There are several DMC versions that offer multi-axis and five-face solutions: the 2100S-6100 SH S Series offer a fixed-column moving table with X-axis travels from 82.7 in to 240.2 in, Y-axis travel of 70 in, and Z-axis travel of 31.5 in, while the 3100P-6100PH P Series feature the same fixed-column moving table with longer travels – X-axis ranges from 122 in to 240.1 in, Y-axis is 90.5 in, and Z-axis is 31.5 in. Table load capacities range from 22,000 lb to 26,400 lb and 22,000 lb to 35,200 lb, respectively.

The large DMC 4000 Series can handle a whopping 44,000 lb of table load with an X-axis travel of 118 in through 236 in, Y-axis travel of 110.2 in to 189 in, Z-axis travel of 31.5 in to 42 in, and a W-axis travel of 39.4 in to 78.7 in on a fixed-column moving table. The SDMC Series includes custom-made, unlimited size, sliding double-column series multi-axis, five-face moving-column and fixed-table gantry mills with X-axis travels ranging from 157-in. to 720-in., Y-axis travels of 72-in. to 236-in., Z-axis travels from 31.5-in. to 42-in., and W-axis travels from 39.4-in. to 78.7-in. Table load capacity is 614-lb./ft.2

Absolute Machine Tools, Inc., 7420 Industrial Parkway, Lorain, OH 44053, 800-852-7825, www.absolutemachine.com.