Mica Band Heaters

Mica Band Heater

Mica heaters are efficient and economical solutions to the heating requirements of many applications. Mica heaters can attain a maximum sheath temperature of 900°F, but with different electrical termination styles, clamping mechanisms, and ability to accommodate holes and cutouts, mica band heaters are successfully used in many applications, but are mostly sought for in the plastics industry.

Mica heaters made by Bucan utilize different types of top grade mica. The thickness of each mica layer is carefully selected in order to balance between the insulating characteristics of mica and the ease of heat transfer from the heating core to the machine barrel.

The resistance wire ribbon used in a Bucan mica heater is not restricted to the capabilities of Nichrome wire. Different alloys are considered for different applications. The internal winding is carefully designed to ensure uniform heat distribution throughout the band heater. To maximize the surface-to-surface contact, our mica heaters are carefully rounded and formed to optimize the grip on a machine barrel. The external metallic protective sheath of Bucan band heaters is made of a special alloy, which expands less than the barrel when heated. This difference in thermal expansion makes the heater grip the barrel firmly once it is energized. This improves heat transfer which extends the life of the mica band heater.

INDUSTRIAL APPLICATIONS FOR MICA BAND HEATERS:

  • INJECTION MOLDING MACHINES

  • PLASTIC EXTRUDERS

  • FOOD INDUSTRY

  • BLOW-MOULDING MACHINES

  • CONTAINER PIPE AND TANK HEATING

  • PHARMACEUTICAL INDUSTRY

Mica band heaters are available with various types of electrical terminations. Each termination has its own unique characteristics, advantages and limitations. When selecting a termination style, the following factors must be taken into consideration: diameter, width, voltage, amperage, operating temperature, electrical safety and cost. Three electrical termination styles are available:

  •  Screw terminals

  •  Lead wire terminals

  •  European plugs

Screw Terminals

Screw terminals mica band heaterStainless steel screw terminals are the most convenient and economical means to connect a band heater to an electrical power source. They are mostly recommended when high amperages (up to 30 amps) are involved. The temperature limitation is 840°F. Screw terminals are available in five styles:

  •  Separate on opposite sides of gap (A)

  •  Along the width side by side (B1)

  •  Along the length side by side (B2)

  •  With protective terminal box (G)

  • With ceramic protective cover (V)

Screw terminals Screw terminals Screw terminals

A Style   

Separate on opposite sides of the gap

B1 Style

Along the width side by side

B2 Style

Along the length side by side

 

Terminal box Terminal box Terminal box

 

Terminal Boxes "G" style 

Terminal boxes eliminate the risk of electrical shock and electrical short by enclosing the terminals in a heavy duty stainless steel box. Cover boxes come in two sizes, G1 and G2. For three-phase and dual voltage applications, special boxes are used.

 

W

L

H

G1

1 5/8"

2"

1 5/8"

G2

2"

1/4"

1 3/4

Ceramic terminal covers "V" style Ceramic terminal covers

Ceramic terminal covers provide a cost effective means of reducing the risk of electrical shock and electrical shorts.

Bucan mica band heaters standard screw size is #10-32. For finer applications, #8-32 screws are available.

Screws have 3/4" height above the barrel with A, B1 and B2 styles.

When ceramic covers (V) are used, the terminals are 1" long.

Heaters that are three-phase, dual voltage, have two independent circuits or a ground terminal, require an additional third or fourth screw.

Screw terminals illustration Three phase, dual voltage and ground terminal screw terminals illustration

 

 

Lead Wire Terminals

High temperature wire is internally connected to the band heater. Lead wire terminalsThis provides a safer electrical connection. However, it is physically impossible to conceal heavy gauge wire under the top metallic sheet. This limits the maximum amperage applicable to 20 Amps. Lead wire terminals are available in three styles:

  •  Armor cable

  • Stainless steel braid 

  • Plain lead wire

Within each style, there are different models of lead wire exits.

ARMOR CABLE

Armor cable provides the best protection against abrasion where a great deal of flexibility is not required. Straight lead exit or 90° bend are the available options for this lead type. Brass fittings are used to secure the termination.

Armor cable straight Armor cable 90 degrees Armor cable 90 degrees

H Style - straight lead exit

GM Style - 90° bend

Armor cable straight exit

 

STAINLESS STEEL BRAID

In applications where there is frequent movement or risk of abrasion, stainless steel braided leads are recommended. Heat shrink sleeving at the end of the leads prevents the braid from fraying.

Leads exit straight Low profile terminal cover Leads exit on each side of gap Leads exit 180 degrees from gap

E Style 
Straight lead exit

 LP Style
Low profile terminal cover

C Style
Used mostly with nozzle heaters

I Style
180° from gap

 

PLAIN LEAD WIRE

Plain leads are used where there is no risk of abrasion or contamination. High temperature wire with fiberglass insulation (840°F) is standard. Teflon insulated wire is also available.

Straight lead exit Leads exiting on both sides of the gap Leads exit on each side of gap 180 degrees from gap

EF Style
Straight lead exit

F Style 
Exiting on both sides of the gap

CF Style
Used mostly with nozzle heaters

IF Style
180° from gap

EUROPEAN PLUGS

European plugs are safe and simple to use. They provide a quick solution in applications where the electrical termination has to be disconnected frequently. They can be used on all our construction and clamping styles. EP terminals provide practical electrical connections when a failed heater has to be replaced. European plugs are available either with the two round prongs (6 mm) or three flat prongs (one of which is ground).

Tangential European terminal box Vertical European terminal box European terminal box at 45 degree angle Three prong with ground European terminal box

K90 Style 
tangential box

K00 Style
vertical box

K45 Style
45° box

K3P Style 
3 Prong with ground

 

 

 

 

Maximum performance and ease of installation are two major considerations when selecting the construction style of a Bucan mica heater. The following are the most common construction styles.

ONE PIECE
 

One-piece construction is used when a band heater can be installed on a barrel without extensively expanding it.
Diameter:5/8"min;22"max
Width: 5/8" min; 14" max

One piece construction mica band heater

TWO PIECE OR MORE
 

Two or more pieces are for ease of installation for a mica heater. A practical choice when the barrel diameter is large.
Diameter:2"min;44"max Width: 5/8" min; 14" max

Two piece construction mica band heater

ONE PIECE FLEXIBLE
 

One-piece flexible mica heaters are used in applications where two-piece construction is not practical, and expanding the heater is necessary during installation. These heaters should not be opened more than twice.

Flexible construction one piece mica band heater

PARTIAL
 

Partial band heaters are recommended where obstructions or complicated holes prevent having complete coverage on the surface of the barrel.

Partial construction one or two piece mica band heater

CONICAL
 

Conical or irregular shaped mica heaters are made to fit unconventional forms. Heat transfer considerations impose limitations on the overall design and construction of these heaters. Our engineers are available to discuss the requirements of each application.

Conical construction mica band heater

SQUARE AND RECTANGULAR
 

Mica heaters can be made square, rectangular or multi-sided to suit your specific requirements.

Square and rectangular construction one or two piece mica insulated heater

REVERSE
 

Reverse mica heaters are used in applications where heating from inside the barrel is required. The outside shell of these heaters is the heating surface and all the terminations and clamps are located on the inside of the heater.
Diameter:3"min;36"max
Width: 1" min; 12" max

Reverse construction band heater

 

The longevity of a band heater is directly related to the heat transfer rate from the heater to the cylinder it is intended to heat. One factor affecting the quality of heat transfer is the clamping mechanism of the band heater.

Band heaters manufactured at Bucan come with different styles of clamping mechanisms. Each style has unique characteristics and advantages. Selection is based on the specific requirements of the application. For assistance in selecting the best available option, contact Bucan.

INDEPENDENT STRAP
 

These straps evenly distribute the drawing force around the band heater by clamping the heater tightly around the surface of the cylinder. This distributed force is transferred to the internal windings, improving heat transfer through effective surface contact and elimination of air gaps.

Independent Strap - Mica Band Heater

BUILT-IN BARREL NUTS
 

This clamping mechanism on a band heater combines the drawing quality of an independent strap with ease of installation. The top sheet is transformed into a strap by incorporating barrel nut fasteners at both sides of the gap. Recommended when holes and cut-outs prevent the usage of an independent strap.

Built in barrel nuts - Mica Band Heaters

SPOT-WELDED STRAPS
 

This construction is similar to the built-in barrel nut style. The fastener section of an independent strap is spot welded on the top sheet on both sides of the gapof the band heater. This construction allows for a heated section under the fastener.

Spot welded straps - Mica Band Heaters

FLANGE LOCK-UP
 

The most economical fastening style on a band heater, flange lock-up is used mostly on narrow band heaters.

Flange lock-up - Mica Band Heaters

WEDGE-LOCK
 

Low profile clamp. Used when clearance above the band heater is limited. A wedge-like clamp slides on the lips of the heater located on both sides of the gap. The normal height from the inner diameter (ID) to the highest point of the wedge lock is 5/16".

Wedge lock clamping - Mica Band Heater

LATCH AND TRUNION
 

Ideal when fast detachment is required for a specific application the band heater is being used for . The clamp is released with a flip of the thumb, eliminating the usage of any tools. The spring loaded 1/4-20 bolt absorbs thermal expansion in the fastened position.

Latch and troniun - Mica Band Heater

HINGES
 

Used when a heater band has two sections. A piano hinge is incorporated on one side of the heater, while the other side can have any kind of clamp. The clearance between the two sections on the side of the hinge is 5/16".

Hinged construction - Mica Band Heater

SPRING-LOADED BARREL NUTS
 

Independent straps, built-in barrel nuts and spot welded straps can have longer screws with incorporated die springs. These springs help to keep the band heater tight during thermal expansion. Only available in 1/4-20 screws.

Spring loaded barrel nuts - Mica Band Heater

CLAMPING PADS
 

Mostly used in two section partial heaters. When an obstruction prevents the usage of a complete band heater, it becomes necessary to create a large gap and fasten the heater to the cylinder on both sides of the gap. It is not advisable to have clamping pads on both sides of the same section of a heater, because thermal expansion might detach the heater from the cylinder.

Clamping pads - Mica Band Heater