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Typical central system sizing
You'll need the following information to determine system size and type
of filtration:
 | Type of material and amount of stock being removed. |
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| The type of machining operations and profile of chips being generated. |
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| Type of MRF to be used. This decision should be made at the inception of the program by
the process engineer, machine supplier, tooling engineer and facilities engineer. |
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| Clarity required. This requirement will determine the type of filtration used and the
flow rate through the filter. |
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| Quantity of MRF (GPM) required for machining operations, flush stations and flush
nozzles internal to the machine (machine and pallet flushing). OEM should provide data
showing calculations, since original numbers are often inadequate. |
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| Temperature control requirements. If MRF is to be temperature controlled, additional MRF
is required for circulation in the chiller loop. |
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| Floor plan layout. A layout showing approximate location of machine(s) is necessary to
determine trench length for trench flushing requirements. |
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Here are the steps to follow in determining system size:
- Machining, flush stations and machine flush = _______ GPM (gallons per
minute)
- High-pressure stations or other unique operations = _______GPM
- Side arm polishing filter if required = ______ GPM
- MRF for trench flushing =
______ GPM
- MRF for temperature control =
______ GPM
Base Total = ______ GPM
When estimating MRF requirements for trench flushing, use
the following:
| Aluminum machining: 1-1/2 to 2 GPM MRF required per linear foot of
trench. |
| Cast iron machining: 2 to 2-1/2 GPM MRF per linear foot of trench. |
| Steel machining: 2-1/2 to 5 GPM MRF per linear foot of trench. When
long stringy chips that form bundles are expected, 5 GPM/ft. may be required, with
large-volume nozzles to dislodge and move the bundles. Additional nozzles may be required
at machines producing chip bundles. |
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| MRF required for the chiller loop = 12-15%
of the total MRF required for all machining, high-pressure stations, polishing filters and
flushing. |
Clean MRF required for clean tank refill = base total x
10%.
| As a chip cake is built up on the septum it becomes more difficult for the
MRF to pass through and the pump output decreases. To compensate for this reduction, an
additional 5% capacity is built into the base system = base total x
5%. |
| When new systems are launched, it is usually necessary to add flush
nozzles in areas where chips are building up or to increase MRF flow to some tools. To
provide reserve MRF for these problem areas, an additional 10% of the base requirement
should be provided = base total x 10%. |
Summary
| Clean tank refill
10% |
| Pump output reduction due to vacuum increase
5% |
| Reserve MRF
10% |
| Total Additional
25% |
| Minimum system requirement = base
total x 1.25 |
Examples
Typical Aluminum Machining System
Required information:
| Material: aluminum |
| Operations: transfer line (drilling, reaming, turning, boring, etc.) |
| MRF: water soluble @ 12:1 |
| Temperature controlled to 72° F +/- 1° |
| High Pressure Stations or Critical Operations: none |
| MRF Clarity: 200 PPM |
Calculation Example
| Total MRF required for machining, machine flush and flush stations: 2,000
GPM (specified by the machine supplier) |
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| MRF required for trench flushing: 400 feet of trench required, as shown on
system layout. |
400 Feet @ 2 GPM/ft. = 800 GPM
MRF required for temperature control: (machine requirements plus trench requirements) x
15% = 2800 x .15 = 420 GPM
Base System Requirement = 2,000 + 800 + 420 = 3,220 GPM
| Additional MRF required for clean tank refill, pump output reduction and
reserve capacity = 25%. |
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| 3,220 GPM x 1.25 = 4,025 GPM total MRF required |
The pump of choice for this system is a vertical turbine 1,400 GPM @ 110' hd with 50 HP
motor.
4,025 GPM Req’d = 2.875 = (3) pumps required
1,400 GPM/pump
3 x 1,400 = 4,200 GPM system size
Filter supplier should verify 110' hd is sufficient to meet pressure requirements at
all drops.
| Since the MRF clarity requirement is 100-200 PPM, a vacuum disposable
media filter will be used. A flow-through wedge-wire panel primary conveyor will be
installed ahead of the filter to remove the larger chips. The primary conveyor will
normally remove 80-90% of the chip load. This increases the time between filter cycles,
which improves filtration and reduces media usage. |
Flow-through wedge-wire primary conveyor:
4,200 GPM = 60 sq.ft. min. wedge-wire required.
70 GPM/sq. ft.
Primary conveyor to have a min. of 60 sq. ft. of wedge-wire.
Disposable media filter: flow rate for aluminum machining = 15 GPM/sq. ft. of filter
area:
4,200 GPM = 280 sq. ft.. of filter area req’d. (min)
15 GPM/sq. ft.
Note: On large systems 2 filters may be required to provide the necessary filter
area.
Typical Cast Iron Machining System
Required information:
| Material: cast iron |
| Operations: General machining (turning,
milling, drilling, tapping) |
| MRF required: 1,800 GPM per machine tool
manufacturer |
| High-pressure or critical operations:
critical tolerances and micro-finish on boring operation |
| MRF required: 320 GPM per machine tool
manufacturer. |
| MRF: water-soluble @ 12:1 concentration |
| Temperature control: none |
| MRF velocity trench: 400 ft., as shown on
layout |
System Equipment Determination
General machining on cast iron usually requires MRF clarity in the 400-500 PPM range. A
wedge-wire drum system can be used.
Critical boring operations require MRF in the 100-200 PPM range. A vacuum disposable
media polishing filter will be used.
System Sizing
Polishing filters:
320 GPM required for precision machines.
Use 400-420 GPM end suction pump
The recommended flow rate through the polishing filter is 10 GPM/sq. ft. of filter
area.
420 GPM = 42 sq. ft.. min. filter area
10 GPM/ ft.
Wedge-wire drum filter:
MRF required for general machining 1,800 GPM
MRF required for polishing filter: provide 450 GPM to polishing filter
MRF required for trench flush:
400 ft. @ 2-1/2 GPM/ft. = 400 x 2.5 = 1,000 GPM
1,800 + 450 + 1,000 = 3,250 GPM = base system requirement
Additional MRF required for clean tank refill, pump output reduction and reserve
capacity = 25%.
1.25 x 3,250 = 4,062 GPM required.
Use vertical turbine 1,400 GPM pumps for this system.
4,062 GPM required = 2.9 = 3 pumps required
1,400 GPM/pump
3 pumps x 1,400 GPM/pump = 4,200 GPM system size
Wedge-wire drums should operate at a flow rate of approximately 20 GPM/sq. ft.
of filter area for best results.
4,200 GPM = 210 sq. ft.. of wedge-wire required
20 GPM/ ft.
Drums are built in standard sizes (diameter and length) which contain a specific amount
of wedge-wire area.
Example: One supplier produces the following series of drums:
3'-0" Diameter 4'-6" Diameter
1'-0" Lg. = 18 sq.ft. w/wire area 2'-0" Lg. = 56 sq. ft..
2'-0" Lg. = 38 sq. ft. w/wire area 3'-0" Lg. = 84 sq. ft..
3'-0" Lg. = 56 sq. ft. w/wire area 4'-0" Lg. = 112 sq. ft.
4'-0" Lg. = 74 sq. ft. w/wire area 5'-0" Lg. = 140 sq. ft.
| To obtain a minimum of 210 square feet of drum filter area, either (3) 3'
diameter x 4' long (3 x 74 sq. ft. = 222 sq.ft.) or (2) 4'-6" diameter x 4' lg. (2 x
112 sq. ft. = 224 sq. ft.) can be used. It is recommended the (3) 3' diameter drums be
used so if one drum must be removed for maintenance the system can continue to operate (at
reduced efficiency) until that drum is replaced. |
Typical Steel Machining System
Required information:
| Material: steel |
| Operations: general machining (turning, milling,
boring, drilling and tapping) |
| MRF required per machine tool supplier = 1,500 GPM 25
psi min. |
| High-pressure or critical operations: none |
| MRF: water-soluble @ 12:1 concentration |
| Temperature control: none |
| MRF velocity trench: 300 ft. as shown on layout. |
System Equipment Determination:
| General machining will produce mostly large chips; turning and boring will produce
some long, stringy chips that will entangle and form bundles. To handle these bundles, a
submerged hinge pan conveyor will be used. The hinge pan will overflow into a vacuum media
filter. If long stringy chips and bundles are not expected, a wedge-wire drum primary
filter with a disposable media polishing filter can be used. |
System Sizing:
MRF required for machining, machine flush and flush stations = 1,500 GPM
specified by machine supplier).
MRF required for trench flush - 300 ft. of trench @ 5 GPM/ft. (use 5 GPM/ft. to
handle expected bundles from turning and boring operations)
300 ft. @ 5 GPM/ft. = 1,500 GPM.
Base system requirement: = 1,500 + 1,500 = 3,000 GPM.
Additional MRF required for clean tank refill, pump output reduction and reserve
capacity = 25%.
3000 GPM x 1.25 = 3,750 GPM total MRF required
Use vertical turbine 1,400 GPM @ 110' hd pumps. Filter supplier should verify adequate
system pressure at machines.
3,750 = 2.68 (3) pumps @ 1,400 GPM required.
Vacuum disposable media filter:
Flow rate for steel machining: = 20 GPM/sq. ft..
4,200 = 210 sq. ft.. of filter area required.
Hinge pan conveyor with tank:
Hinge pan conveyors are available in a wide range of widths. Common widths used in
T&C Operations filtration systems are 36" to 60." The selection of the hinge
pan conveyor width should be a joint decision between engineering and the filtration
equipment supplier based on chip load and similar existing applications. The hinge pan
conveyor tank should be sized to provide approximately (1) minute settling time minimum.
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Contact Chris Roman, 