20-High Mills

Sendzimir 20-High Mills are known worldwide for their ability to roll extremely hard materials to very thin gauges with few, if any, intermediate anneals. They consistently maintain quality aspects that are difficult, if not impossible, to duplicate with other mills.

Advantages Of Using 20-High Mills

Sendzimir Cluster mills have numerous advantages over other mills. One specific advantage is that they make good jobbing mills. It is quite easy to vary the strip material, strip width and/or the strip thickness and set the mill up quickly and efficiently in a matter of minutes, not hours.

The smallest mills roll 4” (100 mm) wide strip down below 0.0001” (2.5 microns). The largest mills roll mostly intermediate gauge materials at widths up to 80” (2 meters) at speeds in excess of 3280 Fpm (1000 Mpm). The small size of the work roll permits superior reductions on very hard materials, such as stainless steel or titanium.

Most rolling mills are custom designed for a specific customer application as well.

Flex Backing Assemblies and Segmented Idler Rolls
Zero Crown Housing
Split Zero Crown Housing
Positionable Sprayboards

Sendzimir’s 20 High Mills offer crucial manufacturing advantages: quality of surface, thin gauge capability, gauge tolerance, and shape.

Quality of Surface

The Work Roll in a Sendzimir Cluster mill is non-chock supported, and thus, can easily be pulled out of the mill by hand. The larger mills will require a roll change cart due to the mass of the roll. In any event, the Work Rolls can be changed in 1 to 3 minutes depending on mill size. Most Sendzimir mills roll a multiple pass schedule (5-7 passes). On the last pass, the Work Roll can be changed out for a fresh pair, and thus, the surface quality of the strip will reflect that fine polish on a new set of Work Rolls. For this reason, most of the 400 series architectural stainless in the world is rolled on Sendzimir mills as the surface finish is paramount.

Strip Shape

The Sendzimir 20-High mill has several shape adjusting capabilities. These are:

Lateral movement of the Tapered (opposed) 1st Intermediate Rolls.
As-U-Roll control of the secondary crown eccentrics in each saddle across the width of the mill.
Double As-U-Roll Mill Configuration
Flexible Backing Assemblies and Segmented Idler Rolls

The small diameter of the work rolls also permits greater responsiveness to shape control mechanisms.

Thin Gauge Capacity and Gauge Tolerance

The cascading structure of the 20-High design allows for a very small Work Roll Diameter. The advantage of this work roll diameter is that it provides for a high specific pressure on a very small contact area. As a result, we can take higher reductions at thin gauges with up to 80%+ total reductions on stainless and 92%+ on non-ferrous.

Because of the very small contact area, the mill housing realizes a relatively small total RSF (Roll Separating Force). And therefore, because the RSF is lower, the mill appears stiffer so that there is less output variation on the strip thickness. This fact, together with our patented Zero Crown Housing, ensures good strip tolerance across the width of the strip with minimum variation from operator to drive side of the mill. This principle holds for softer materials as well as the very hard-to-roll materials.

For instance, a ZR 22-50, 50” mill has a maximum RSF is 1,675,000 Lbs (7468 kN) where a typical 4-High of the same width would be on the order of 5,000,000 lbs. (22295 kN)! The reduced rigidity of 4-High or 6-High mills caused by higher RSF, results in roll deflection and flattening, and therefore, thickness variation, especially near the center of the strip, is increased.

Materials Rolled and Thicknesses Obtained

Sendzimir’s 20-High Cluster mills can roll any metal our clients may need, and we specialize in exceptionally hard metals.

Explore some of the listed options Sendzimir offers our clients:

Autobody sheet
Deep and extra-deep drawing, low-carbon steels
Feedstock for the manufacture of tinplate
Austenitic, martensitic, and ferritic stainless steels
Non-oriented as well as grain-oriented silicon steels
High-carbon steels for items such as razor blades and saws
Nonferrous metals, such as brass and special alloys of brass, copper, bronze, beryllium copper, and bimetals
Metals, such as aluminum, zirconium, molybdenum, silver, gold, tantalum, titanium, cobalt, and nickel, and their alloys, such as aluchrom

Mill Section Nomenclature Designations

Standard Sendzimir Mill Models

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Mill Section	Nominal Work Roll Diameter	Backing Bearing Diameter	Strip Width Min – Max	Roll Separating Force
ZR 32	0.25”	1.875”	4.5 – 8.75”	5,200 lb/in
ZR 32	6.35 mm	47.6 mm	114 – 222 mm	93 kg/mm
ZR 34	0.400”	3.000”	7.5 – 17.5”	8,400 lb/in
ZR 34	10 mm	76.2 mm	190 – 445 mm	150 kg/mm
ZR 24	0.844”	4.724”	8.5 – 19.5”	13,300 lb/in
ZR 24	21.5mm	120mm	215 – 500mm	238 kg/mm
ZR 33	1.125”	6.299”	13 – 37”	17,700 lb/in
ZR 33	28.5mm	160mm	330 – 940mm	316 kg/mm
ZR 25	1.260”	13.23”	13.8 – 28”	22,000 lb/in
ZR 25	32mm	190mm	350 – 710mm	393 kg/mm
ZR 23	1.578”	8.858”	19 – 56”	24,900 lb/in
ZR 23	40mm	225mm	480 – 1425mm	445 kg/mm
ZR 22	2.125”	11.811”	25 – 80”	33,200 lb/in
ZR 22	54mm	300mm	635 – 2030mm	593 kg/mm
ZR 22B	2.500”	11.811”	25 – 80”	33,200 lb/in
ZR 22B	64mm	300mm	635 – 2030mm	593 kg/mm
ZR 21B	3.543”	16.000”	36 – 90”	45,000 lb/in
ZR 21B	90mm	406.4mm	914 – 2286mm	804 kg/mm

Download 20-High ZR Mill Section Specifications

Our innovative staff of engineers and designers is available to discuss revamp work on your existing mill or new mills designed to your specifications. Contact Us Today!