Union BF 130

The W-axis is the boring spindle's longitudinal extension — the spindle slides in and out of the boring head along its own axis (independent from the Z-axis machine column travel). The W-axis extension on the Union BF 130 provides up to 800 mm of additional reach for deep boring without repositioning the column. The W-axis (spindle extension) combined with the Z-axis (column travel) gives a combined boring depth far exceeding what the column travel alone provides. For deep bores (400–700 mm depth) in large housings, the W-axis extension is critical — positioning the column near the bore and using W-axis extension to reach the bore bottom without deflection.

For 400 mm bore diameter at 600 mm depth: the boring bar diameter is typically 100–120 mm (approximately 25–30% of bore diameter for L/D ratio management). At an L/D ratio of 6:1 (600 mm depth / 100 mm bar), the boring bar is at the limit of rigidity for fine boring operations — vibration and chatter are possible at this L/D ratio. Union's 130 mm spindle provides the mounting rigidity for large-diameter boring bars. For deep large bores, intermediate supports (steady rests) on the boring bar reduce effective L/D ratio. For rough boring, L/D ratios of 8:1 are manageable; for precision finish boring (±0.01 mm), L/D should not exceed 5:1 without steady rest support.

A large HMC (like the Burkhardt+Weber BW300 or MAG HMC series) has a pallet system and automatic tool change optimized for prismatic parts under ~5,000 kg. The Union BF 130 floor boring machine handles workpieces from 5,000 to 80,000+ kg that HMC pallets cannot accommodate. HMCs provide higher spindle speeds (3,000–8,000 RPM) for better productivity on smaller features; floor boring machines provide the structural rigidity for 130 mm boring bars on large-diameter precision bores. For large turbine housings weighing 10,000+ kg with 200–500 mm precision bores, only floor boring machines provide the required capability — no HMC can handle these workpieces.

The Union BF 130 achieves bore roundness of 0.005–0.010 mm (5–10 µm) on standard production boring with proper setup and tooling. Bore-to-bore alignment accuracy across multiple bearing bores (critical for shaft alignment in rotating equipment) depends on the machine's positioning accuracy (±0.005 mm) and the calibration of the rotary table B-axis. For turbine and compressor shaft bearings requiring concentric alignment within 0.01–0.02 mm Total Indicated Runout (TIR), the BF 130 meets these requirements with proper setup using precision boring bars and in-process gauging. Higher precision requirements (0.003 mm TIR) require additional in-process measurement and compensation.

The Union BF 130 requires a reinforced concrete foundation of 400–600 mm thickness (machine size dependent) with vibration isolation mountings. Foundation design must account for the machine's static weight (35,000–80,000 kg), dynamic cutting forces during heavy milling (up to 50+ kN), and the workpiece weight (up to 80,000 kg) on the floor plate or rotary table. Union provides detailed foundation drawings for each machine configuration — the foundation must be completed and cured before machine delivery. Installation includes precision leveling of the machine column and floor plate to within 0.02 mm/m flatness. Foundation work and installation typically add $50,000–$150,000 to the total project cost.