United Grinding (Blohm) CNC Grinding Machines

Blohm Planomat HP 624

$250,000 - $380,000 Updated 2026-03-16

Key Specifications

Table Size

600 x 400 mm (23.6 x 15.7 in)

Spindle Power

11 kW (14.7 hp)

Accuracy

0.001 mm (0.00004 in)

table traverse x

750 mm (29.5 in)

crossfeed y

420 mm (16.5 in)

vertical infeed z

450 mm (17.7 in)

Overview

The Blohm Planomat HP 624 is a mid-to-large CNC surface grinding machine designed for production-scale flat, angle, and step surface grinding of larger workpieces — large mold plates, die shoes, machine beds, and precision structural components that exceed the capacity of smaller surface grinders. With a 600 x 400 mm (23.6 x 15.7 in) table capacity, the HP 624 handles the significant-size mold base work common in large injection mold facilities and stamping die shops.

The HP 624's spindle delivers 11 kW (14.7 hp) at up to 35 m/s wheel speed, providing aggressive stock removal capability on large cross-sections of hardened tool steel and cast iron. The electromagnetic chuck covers the full 600 x 400 mm table, enabling secure workholding of large plates without fixture setup time. CNC axes (X table traverse, Y crossfeed, Z vertical infeed) are fully programmable for automatic grinding cycles including roughing and finishing passes within a single program.

Blohm designed the HP 624 with the mold shop in mind — the machine's ability to grind large mold plates to precision flatness (under 0.005 mm across 600 mm) and parallelism is the primary qualification criterion for mold base preparation. Properly maintained mold plates are fundamental to producing flash-free, dimensionally consistent injection-molded parts, making the surface grinder a key piece of equipment in any precision mold shop.

At $250,000-$380,000 new, the HP 624 competes with Okamoto ACC-6.4DX and Chevalier FSG-6480ADII machines in the large-format CNC surface grinder segment. Blohm's premium positioning reflects United Grinding build quality and C.O.R.E. platform integration for shops running multiple United Grinding brands.

Full Specifications

Parameter	Value
Table Size	600 x 400 mm (23.6 x 15.7 in)
Table Traverse X	750 mm (29.5 in)
Crossfeed Y	420 mm (16.5 in)
Vertical Infeed Z	450 mm (17.7 in)
Max Wheel Speed	35 m/s (6,890 fpm)
Wheel Dimensions	350 x 40 x 127 mm (13.8 x 1.57 x 5 in)
Spindle Motor Power	11 kW (14.7 hp)
Table Speed	1-25 m/min
Positioning Accuracy	0.001 mm (0.00004 in)
CNC Control	Fanuc with C.O.R.E. platform
Machine Weight	~5,000 kg (11,023 lb)

Strengths & Limitations

Strengths

600 x 400 mm table handles large mold plates and die shoes that smaller surface grinders cannot accommodate in a single setup
11 kW spindle provides aggressive stock removal capability on large hardened steel cross-sections
Full electromagnetic chuck over the entire 600 x 400 mm table enables secure, distortion-free workholding of large plates
CNC automation enables consistent roughing and finishing cycles without manual intervention
C.O.R.E. platform consistency for United Grinding multi-brand shops
0.001 mm positioning accuracy for precision parallelism and flatness on mold plate grinding

Limitations

5,000 kg machine weight requires a solid foundation and significant site preparation
$250K-$380K represents a significant premium over Chevalier and Okamoto equivalents at similar table capacity
Blohm's North American dealer network for surface grinders is smaller than Okamoto's
Large electromagnetic chuck requires substantial electrical power for magnetization — operating cost consideration

Best For

Large injection mold shops grinding mold plates, cavity retainer plates, and support plates to precision flatness Stamping die shops grinding large die shoes, punch holders, and die plates for progressive die tooling Precision machine builders grinding large machine bed and column mating surfaces for precision machine tool production Tool and die makers requiring consistent flatness and parallelism across large workpieces in hardened tool steel Production surface grinding of large hardened components in automotive tooling and energy equipment manufacturing

Frequently Asked Questions

01 What flatness does the Planomat HP 624 achieve on a large mold plate?

The HP 624 achieves flatness of 0.005 mm (0.0002 in) or better across the full 600 x 400 mm table area on well-conditioned hardened steel plates. This level of flatness is appropriate for precision mold plates where flash-free parting requires consistent mold plate contact across the full mold face. Achieving this flatness requires appropriate wheel dressing, coolant management, and workpiece temperature stability.

02 How does the HP 624 compare to the HP 412?

The HP 624 has a significantly larger table (600 x 400 mm vs 400 x 200 mm), more spindle power (11 vs 5.5 kW), a larger wheel diameter (350 vs 250 mm), and handles workpieces twice as large. The HP 624 costs $70K-$100K more. For shops regularly grinding mold plates over 400 mm in either dimension, the HP 624 is required. The HP 412 is appropriate for smaller components.

03 Can the HP 624 use CBN grinding wheels?

Yes, the HP 624 supports CBN (cubic boron nitride) grinding wheels in appropriate diameter and specification. CBN wheels provide longer wheel life and better thermal stability than aluminum oxide on hardened steel, reducing the frequency of wheel dressing and improving consistency on long grinding cycles. CBN wheel costs are higher than conventional wheels but are often justified on production grinding of large hardened steel batches.

04 What is the cycle time for grinding a 500 x 300 mm mold plate?

A typical roughing and finishing cycle for a 500 x 300 mm mold plate (10mm stock removal) on the HP 624 takes approximately 30-60 minutes depending on material hardness, wheel specification, and finish requirement. The CNC program manages the roughing passes (heavier infeed, higher table speed) and finishing passes (light infeed, lower table speed) automatically within a single program.