Dual-Spindle Gun & BTA Drilling for Large Steel Plates

Customer Background

The customer is a heavy steel fabricator producing large structural and machine-frame components — press frames, machine bases, boom sections, and flanges up to 3 meters across. These parts carry dense hole patterns: bolt circles, bushing mounts, and fluid passages that must all be positioned accurately across the full plate.

The Challenge

Large-format plate drilling is a productivity problem as much as a precision problem:

Hundreds of holes per plate. A single large plate can carry 200-300 holes in grid and bolt patterns. Single-spindle drilling machines produce them one at a time, and on a 3-meter plate the positioning time adds up as much as the cutting time.

Paired-hole geometry. Many designs call for hole pairs at a fixed spacing — bolt pairs, bushing mounts, and guide pin holes. Each pair must share a consistent center distance across the whole plate, which is hard to hold when every hole is positioned individually.

Mixed diameters on one part. Plates commonly need both small Ø10-20mm gun-drilled holes (fasteners, pilot holes) and larger Ø20-40mm BTA holes (through-passages, mounting bores). Historically these were done in separate setups or on separate machines.

Thick sections. Structural plates can be several hundred millimeters thick. Drilling Ø40mm holes through such sections requires deep-hole technique — straightness and chip evacuation — rather than conventional twist drilling.

Large-format coverage. A plate wider than the machine table requires repositioning and re-fixturing, which breaks pattern registration and adds setup hours.

The Solution

RuidCNC supplied a Deep Hole Drilling Machine for Steel Plate (RD3020-06S) — a dual-spindle machine sized for large-format plates:

• Dual spindles at adjustable 170–220mm centerline spacing — bolt pairs and bushing pairs drilled in one pass at a consistent center distance
• Gun + BTA drilling in one machine — Ø10-20mm gun drilling for fasteners and pilot holes, Ø20-40mm BTA drilling for passages and mounting bores, with no tool-system changeover
• 3000 × 2000mm worktable, 20-ton capacity — full large-format plates held in a single setup, preserving grid registration edge to edge
• 800mm hole depth — drills through thick structural sections in continuous passes
• 2-10 MPa high-pressure coolant with 2000L tank — sustained high-flow chip evacuation for long, dense drilling programs
• Reinforced 50-ton machine structure — rigid under 20-ton workpieces for stable hole position across the whole table

Key Machine Specifications

Parameter	Specification
Drilling diameter (gun drilling)	Ø10 – Ø20 mm
Drilling diameter (BTA)	Ø20 – Ø40 mm
Max hole depth	800 mm
Spindles	2 (centerline 170–220 mm, adjustable)
Max workpiece diameter	Ø3,000 mm
Worktable dimensions	3000 × 2000 mm
Max load capacity	20 tons
Coolant pressure	2 – 10 MPa

Results

Metric	Single-Spindle CNC Drilling	RD3020-06S Dual-Spindle	Improvement
Holes per shift (Ø25mm BTA × 600mm)	420	780	86% increase
Hole-pair spacing accuracy	±0.08 mm	±0.03 mm	63% better
Bolt-circle position error	±0.10 mm	±0.035 mm	65% better
BTA bore surface finish (Ra)	2.2 µm	1.1 µm	50% better
Setups per plate	2	1	Eliminated
Scrap / rework rate	2.8%	0.5%	82% reduction

Process Validation

The process was validated through:

• Hole position and hole-pair spacing measurement on a CMM across the full plate
• BTA bore surface finish inspection on sample holes
• Through-hole alignment checks on stacked plate sections
• First-article dimensional inspection against the drawing

Conclusion

The RD3020-06S converts large-format plate drilling from a slow, single-hole operation into a two-hole-per-pass process. With dual spindles at adjustable centerline spacing and a 3000 × 2000mm table that holds a full plate in one setup, the customer increased holes per shift by 86% while holding hole-pair spacing and bolt-circle position across the plate. For steel fabricators drilling dense structural patterns into press frames, bases, and flanges, the RD3020-06S is a direct path to shorter cycle times and consistent pattern registration.

Figures are representative of typical applications.