Watlow MI Band Data sheet

W A T L O W

Band Heaters

MI Barrel and Nozzle

The MI band is a high performance
heater. Its performance and name
are derived from Watlow’s exclusive
mineral insulation—a material that
has much higher thermal
conductivity than the mica and
hard ceramic insulators used in
conventional heaters.

A thin layer of the “high” thermal
conductive MI material is used to
electrically insulate the element wire
from the inside diameter of the
heater sheath. A thicker, “low”
thermal conductivity layer backs up
the element wire, directing the heat
inward toward the part that is being
heated. The result is more efficient
heat transfer—a performance
solution that lowers element wire
temperatures and increases
heater life.

Performance Capabilities

• Heater operating temperatures to
760°C (1400°F)

• Watt densities to 230 W/in
(35.6 W/cm2) available on
small diameter nozzle bands

• Watt densities to 100 W/in
(15.5 W/cm2) available on large
diameter barrel bands

Features and Benefits

Operating temperatures to

F)

760

C (1400

°

°

• Safely melts resins such as
Peek®, Teflon®, Ultem®and

®

Zytel

Higher watt densities

Contributes faster heat-up and

•
through-put for increased
productivity

High thermal conductivity of MI
and low mass construction

Gives an almost instant r

•
to temperature control

Eliminates ther

•

mal lag and
temperature overshoot associated
with ceramic knuckle heaters

2

2

esponse

Stainless steel co

old design

f

ver and side

• Resists contamination by
ow of plastic or other

overfl

owing materials

ee-fl

fr
Side folds tur

•

n to the inside
diameter rather than the outside
diameter

lamp bar

ermanentl

P

y attac

hed c

• Eliminates cumbersome
clamping straps, which make
installation easier

Same day shipment on all stock heaters with post

•
erminals or Type B leads.

t

Thick Low
Conductivity
MI Backing

Thin High
Conductivity
MI Insulation

Stainless
Steel Sheath

Element Wire in
Mineral Insulation

Coiled or Sinuated
Wire Element

Applications

Extruders

•

• Blown film dies

• Injection molding machines

Other cylinder heating

•

applications

s

®

on

efl

T

and Zytel®ar

of E.I. du Pont de Nemours & Company

®

Ultem

is a registered trademark of General

Electric Corporation.

®

is a registered trademark of Greene,

Peek
Tweed & Company.

egistered trademarks

e r

Band Heaters

.

1

Band Heaters

MI Barrel and Nozzle

Applications and Technical Data

The

Physical Limitations of

Variations

table shows you the
availability of widths, inside
diameters and terminations for
Watlow’s MI band heaters. To make
sure the available terminations will
meet your application needs, refer

Physical Limitations of Variations

Widths I.D. Available—in. (mm)

in. (mm) 1 pc. Construction Expandable 2 pc. Construction Available Terminations

Minimum Maximum Minimum Maximum Minimum Maximum

in. (mm) in. (mm) in. (mm) in. (mm) in. (mm) in. (mm)

1 (25.4) 1 (25.4) – 14 (355.6) 3 (76.2) – 14 (355.6) 3 (76.2) – 14 (255.6) All

3

⁄8 (34.9) 1 (25.4) – 3 (76.2) 3 (76.2) – 6 (152.4) 3 (76.2) – 6 (152.4) All

1
11⁄2 (38.1) 1 (25.4) – 14 (355.6) 3 (76.2) – 14 (355.6) 3 (76.2) – 28 (711.2) All
2 (50.8) 11⁄4 (31.8) – 14 (355.6) 3 (76.2) – 14 (355.6) 3 (76.2) – 28 (711.2) All

1

⁄2 (63.5) 11⁄4 (31.8) – 14 (355.6) 3 (76.2) – 14 (355.6) 3 (76.2) – 28 (711.2) All

2
3 (76.2) 11⁄4 (31.8) – 14 (355.6) 3 (76.2) – 14 (355.6) 3 (76.2) – 28 (711.2) All

31⁄2 (88.9) 13⁄4 (44.5) – 14 (355.6) 3 (76.2) – 14 (355.6) 3 (76.2) – 28 (711.2) All - Except 90° “B” Leads
4 (101.6) 2 (50.8) – 14 (355.6) 3 (76.2) – 14 (355.6) 3 (76.2) – 28 (711.2) All

1

⁄2 (114.3) 21⁄4 (57.2) – 14 (355.6) 3 (76.2) – 14 (355.6) 3 (76.2) – 28 (711.2) All

4
5 (127.0) 2
51⁄2 (139.7) 23⁄4 (69.85) – 14 (355.6) 3 (76.2) – 14 (355.6) 4 (101.6) – 28 (711.2) Post Terminals, SLE
6 (152.4) 3 (76.2) – 14 (355.6) 3 (76.2) – 14 (355.6) 4 (101.6) – 28 (711.2) All
7 (177.8) 4 (101.6) – 14 (355.6) Post Terminals, SLE

1

⁄2 (63.5) – 14 (355.6) 3 (76.2) – 14 (355.6) 4 (101.6) – 28 (711.2) All - Except 90° “B” Leads

N/A

N/A

N/A

to the illustrations of termination
variations in this section.

If you need to exceed limitations
shown, contact your Watlow sales
engineer or authorized distributor.

N/A

General Limitations:

• Maximum width of 1 inch (25 mm)
diameter heater is 1.5 inches wide
(38 mm).

Maximum heater width = 2x heater

•
diameter

Minimum I.D. for T

•

ype B, C, E and H

leads = 1 inch (25 mm)

• Minimum I.D. for Type B

—

90 degree

leads = 11⁄8 inches (28 mm)

• Maximum lead amps: 12.5A per pair

• Maximum amps (post terminals): 30A
per pair

• Minimum diameter and width for SLE
is 4 inches x 11⁄2 inch width

SLE maximum 17.0 amps

•
90 degr

•
250V

ee bends not available over

Å(ac)

Standard Gaps:

•≤3 inches = 1⁄8 inch nominal

• 3 inches ≤6 inches = 1⁄4 inch
nominal ±1⁄8 inch

• 6 inches ≤14 inches = 3⁄8 inch
nominal ±1⁄8 inch

• >14 inches = 1⁄2 inch nominal
±1⁄4 inch

2

W A T L O W

100

Watt Density–W/in

2

Part Temperature–°C

200

300

400

500

600

1300

200

1200

1100

1000

900

800

700

600

500

400

300

10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230

700

Part Temperature–°F

5 10 15 20 25 30 35

Watt Density–W/cm

2

1

1

/

2

in. (38.1 mm) I.D.

3 in. (76.2 mm) I.D.

6 in. (152.4 mm) I.D.

10 in. (254 mm) I.D.

1

4

i

n

.

(

3

5

5

.

6

m

m

)

I

.

D

.

&

2

P

i

e

c

e

1

2

i

n

.

(

3

0

4

.

8

m

m

m

)

I

.

D

.

Band Heaters

MI Barrel and Nozzle

Applications and
Technical Data

Calculating Watt Density

Watt density is the amount of
wattage per square inch of heated
area. To determine watt density,
divide the total wattage by the
heated area.

Watt Density =

To apply this equation, we must
define the term "heated area."

Total Watts

Heated Area

Heated area is the total contact
surface of the heater less areas of
no-heat that are found around
terminals, mounting holes, etc.

Heated Area =
Total Contact Area - No-Heat Area

To calculate the heated area:

1.Locate the no-heat factor from
the chart below that corresponds

Type Factor

in.

1 pc. lead unit Type B, C,
H, E or 90°B 1.37
1 pc. post terminal 1.60
1 pc. expandable post term 3.18
1 pc. expandable lead unit 3.00
True 2 pc. post term 3.20
True 2 pc. leads 2.74
SLE 3.68

to the type of heater being
considered.

2.To use the formula below, insert
the no-heat factors, diameter and
width (in inches).

Heated Area =
(3.14 x Diameter - No-Heat
Factor) x Width

Band Heaters

Maximum Allowable Watt Density

The following derating factors apply
to the

Maximum Allowable Watt

Density

chart, which are shown in
both inch base and metric for your
convenience. Please review these
factors and the chart to determine
the correct watt density curve for
your application.

Derating Factors:

• For units over two inches
(51 mm) in width, multiply watt
density by 0.80.

• In applications where unusual
operating conditions are present,
such as irregular mounting
surfaces, contact the Watlow
factory in St. Louis, Missouri,
for watt density limitations.

Maximum Allowable Watt Density

Allowable watt density for 11⁄2 in. wide
MI band heaters:

• Moderate cycling

• Heaters properly clamped

• Heaters mounted on a smooth cylinder

• For two-piece units used in
vertical applications, refer to

Clamping Matrix Application
Guide

.

• For applications where insulating
blankets are used, multiply W/in
(W/cm2) by 0.75.

2

3