Sand molding machine

01

Control mould hardness with filling and squeeze settings

AFS's Modern Casting describes mould hardness as the mould's resistance to indentation, closely tied to sand packing density. Too little hardness can cause shrink defects, porosity from mould-wall movement, poor surface finish and run-outs; too much can cause gas defects from low permeability, scabs, buckles, burn-on, penetration and poor shakeout. Both too high and too low a squeeze pressure can give low hardness, as can too short a shot time, low blow pressure or uneven filling; machines with zoned squeeze heads help even out density, and worn tooling or poor pattern-plate venting can cause local soft spots. [1]

The article recommends mould hardness or strength testers on the line, notes that B-scale (round penetrator) is the scale it reports green-sand foundries using, and says moisture and clay type also shift hardness: excess moisture risks washout, too little gives weak moulds, and high sodium bentonite can reduce flowability and leave soft areas without adequate aeration. [1]

Give the supplier the castings and alloys, mould size and cope/drag heights, moulds per hour, core setting needs, sand system (green sand properties and temperature), pattern plates, mould handling and pouring line, compressed air and power, and the mould hardness targets and test method.

02

Size the machine: mould size, rate, air and sand

Juneng's JN-FB series flaskless machine turns the flasks 90°, shoots sand vertically from the top, squeezes and strips moulds with a horizontal parting line; the drag slides out for core setting. The series lists mould sizes from 500 × 600 mm to 650 × 750 mm with cope and drag heights linearly adjustable within 130–250 mm. The JN-FB03 runs at up to 115 moulds per hour excluding core setting, using 1.2 Nm³ of air per mould at 0.5–0.55 MPa, with mould weights of 117–201 kg; the larger JN-FB04 runs at up to 95 moulds per hour using 2.5 Nm³ per mould, with 195–325 kg moulds. Hydraulics are driven by servo-controlled pumps. [2]

Editorial calculation: 115 moulds per hour is a 31 s cycle; at 1.2 Nm³ per mould the machine uses about 138 Nm³ of air per hour, and at 117–201 kg per mould it needs about 13–23 tonnes of prepared sand per hour. For the JN-FB04, 95 moulds per hour is a 38 s cycle and about 240 Nm³ of air per hour. [2] Size the sand plant, air supply and pouring line to the rate you will actually run, including core-setting time.

A second maker's horizontally parted flaskless range shows how rate, air and power scale with mould size. Sinto America lists its FBMX machines with top and bottom aeration sand filling, squeeze pressure balance control, mould-height feedback control to cut sand use, a maximum squeeze pressure of 1.0 MPa and a Mitsubishi PLC. Average maximum moulding rates fall from 163 moulds per hour on the smallest model to 100 on the largest, excluding core-setting time. [4]

Editorial calculation: at its rated speed the FBMX-II uses 163 × 2 ≈ 326 Nm³ of air per hour and the FBMX-V 100 × 6.5 = 650 Nm³ per hour, against about 138 Nm³ per hour worked out above for the Juneng JN-FB03 at 1.2 Nm³ per mould. The FBMX-V mould face (0.66 m²) is about 2.7 times that of the FBMX-II (0.25 m²) at 61% of its moulding rate. Size the compressor from the air per mould times the moulds per hour you plan to run. [4] [2]

03

Compare vertically parted lines on speed, mismatch and changeover

DISA's DISAMATIC D-line page describes its vertically parted green-sand moulding machines as reaching moulding speeds up to 555 moulds per hour, for an annual capacity of 30,000–40,000 tonnes, with mismatch of ±0.1 mm and automatic pattern changes in 60 seconds. It lists an automatic core setter it says inserts cores 10 times faster, and an automatic filter setter that lets filter jobs run at full moulding speed, 15% faster than using the core setter. [3]

The page also lists automatic and precision mould conveyors to move moulds through pouring without distortion at high speed. Compare these figures with horizontally parted flaskless machines such as the Juneng JN-FB series above on mould size, cycle time and core-setting access. [3] [2]

Editorial calculation: 555 moulds per hour is one mould about every 6.5 s.

State casting size and weight, required moulds per hour with and without cores, filter use and the mismatch you can accept, and ask for the machine's speed on cored and filter jobs, mould size range and pattern change time.

04

Servo-hydraulic flaskless, multi-piston and jolt-squeeze machines with sand plants

Juneng lists servo-hydraulic flaskless moulding machines and mould conveyors; Sanzhuji lists horizontal and vertical flaskless, multi-piston and jolt-squeeze moulding machines with sand plants; HQAMUR (Huaqing) lists flaskless automatic moulding machines and resin-sand lines; Bestech and ZMZO list sand moulding machines with core shooters and sand plants.

05

Sand hopper and shot system, squeeze head, pattern plates, flasks and hydraulic drive

The first three rows set mould hardness: Modern Casting ties soft moulds to short shot time, uneven filling, squeeze pressure set too high or too low, and poor pattern venting. [1]

06

Squeeze force, mould size, cycle time, air pressure and mould hardness for a moulding machine quotation

Read the cycle-time row with core setting included: 115 moulds an hour is a 31 s cycle on the Juneng example, while a vertically parted DISA D-line runs up to 555 moulds an hour, about 6.5 s each. [2] [3]

07

Send the casting, mould and line data together

Paste it into your enquiry below or into an email to a maker, then replace every bracket.

Castings: [alloy; weight; size; cores]
Mould: [size; cope and drag heights; parting]
Rate: [moulds per hour incl. core setting]
Sand: [green sand properties; temperature; supply rate]
Quality: [mould hardness targets; test method]
Site: [compressed air; power; pouring line; foundation]

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