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2. Welcome to this section, Fluxtrol Materials on Induction Coils. Fluxtrol Inc. is a world leading manufacturer of magnetodielectric materials for induction heating controllers

3. Primary materials are:

- Fluxtrol A

- Fluxtrol 50

- Ferrotron 559H

4. Fluxtrol Inc. also manufactures other standard and custom materials such as:

- Ferrotron 119

- Fluxtrol 25

- Custom materials

5. Fluxtrol Inc. manufacturers a large variety of sizes and shapes. Special shapes may be made on request

6. Materials in the Fluxtrol and Ferrotron families, which are designed primarily for induction heating, may be used in many other applications (such as sensors, antennas etc.)

7. Fluxtrol Material Features: Fluxtrol and Ferrotron materials cover the whole frequency range used in induction heating

8. Magnetic permeability is sufficient for induction heating applications

9. All materials have excellent machinability and good mechanical strength; they may be used as structural components of the coil

10. Ferrotron materials have good electrical strength and may withstand applied voltage up to several hundred volts

11. Temperature resistance is high enough; in critical applications additional measures of thermal management may be used

12. Losses may be removed by quenchant, by contact to the coil tubing, by special cooling plates or water channels machined directly into the material

13. All materials are resistant to oil, hot water and polymer quenchants; small surface rusting may be prevented by etching or coating

14. Uses of Fluxtrol Materials in Induction Heating: Major applications: Cylindrical OD coils for static hardening

15. Single-turn OD scan coils (parts with a sharp fillet)

16. Complex coils (wheel hubs, CVJ stems, etc.)

17. ID coils (cylinder liners, ID gears, etc.)

18. Channel coils (fasteners, machine tool brazing, etc.)

19. Gear heat treating coils (single and dual frequency, tooth by tooth etc.)

20. Local heating for bending and other deformation

21. Brazing and soldering

22. Emerging applications: Single shot coils for axles and shafts

23. Rotational crankshaft coils

24. Seam annealing coils

25. Induction tempering

26. Packaging technology

27. Shielding of workpiece and equipment parts

28. Inductive coupled low temperature plasma

29. Impeders for tube welding

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31. Properties of Fluxtrol and Ferrotron Materials

32. Fluxtrol Primary Products: This chart shows the physical characteristics of primary and specialized products. Note that frequency ranges and resistivity values are only for reference.

33. Magnetization Curves for Fluxtrol Products: Compared to laminations and ferrites, Fluxtrol materials are almost linear. This means that Fluxtrol controllers do not generate distortions in coil currents or voltage waveforms. Distortions result in additional reactive power of the coil and additional losses in transformer and capacitor battery.

34. Permeabilities were measured at 10 kHz for a favorable direction of magnetic flux flow. These data remain valid for all frequency ranges specified for particular materials.

35. Magnetic Permeability of Fluxtrol Products: Fluxtrol A material can support permeability above 50 at high magnetic loading (flux density up to 14000 Gs), which is essential for high power and low frequency applications.

36. Range of flux density in measurements is sufficient for the majority of applications. Materials may be used even at higher load at proper conditions (short heating cycle, intensive heat removal).

37. Permeabilities were measured at 10 kHz for a favorable direction of magnetic flux flow. These data remain valid for all frequency ranges specified for particular materials.

38. Material Anisotropy: When material has different properties in different directions they say that material is Anisotropic.

39. Laminations are highly anisotropic because all properties in the plane of a sheet are very different than in perpendicular direction of the stack.

40. Ferrites have low anisotropy except in special types of material.

41. Fluxtrol composites are pressed materials and therefore have certain anisotropy, which depends on material composition, size and shape of particles and manufacturing technique.

42. Magnetic and thermal properties are higher in the direction perpendicular to pressing.

43. Anisotropy must be taken into account in concentrator design and manufacturing in heavy loaded applications (high power density, high frequency, long heating time).

44. Anisotropy of Fluxtrol and Ferrotron materials:

Fluxtrol A has significant anisotropy due to its structure. In a plane perpendicular to the pressing direction_permeability and thermal conductivity are significantly higher. Also losses are lower when magnetic flux flows in a plane perpendicular to pressing direction

45. Ferrotron 559H has low anisotropy due to higher content of binder and different material structure

46. Fluxtrol 50 has anisotropy in between that of Fluxtrol A & Ferrotron 559H

47. Anisotropy of Fluxtrol A allows this material to have an exceptional combination of high electrical resistivity, thermal conductivity and permeability with proper orientation

48. Optimal orientation of material in C-shaped concentrator provides high permeability, lower losses and good heat transfer from material to the coil copper

49. Optimal Cutting of Fluxtrol Material from Blank Stock: As shown in Chapter 5, for the majority of applications, permeability values above 30-50 do not change the controller performance. Main reasons for optimal material orientation is control of the concentrator temperature, which depends on losses, heat removal conditions and duty cycle.

50. Material orientation is mostly essential for heavy loaded applications such as scanning or single-short hardening when concentrator losses are removing continuously by heat transfer to the copper in the process of heating. For these cases orientation BEST is strongly recommended with orientation N1 as a second choice. It is because the highest value of thermal conductivity is more important than slightly higher magnetic losses in the poles.

51. For short heating cycles such as contour gear hardening, orientation N2 is the second choice after best because of lower losses in the poles than in the case N1 and lower influence of thermal conductivity on concentrator temperature.

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53. Electrical Resistivity and Resistance: Resistivity strongly depends on material type

54. It is higher in direction of pressing

55. Can drop after long-term exposure to temperature above 250 C

56. Resistivity is not a major material performance parameter; only a level of resistivity should be controlled.

57. HF materials require higher resistivity to withstand higher voltages induced inside the concentrator or applied to it

58. Fluxtrol A is a unique material, which has high permeability and internal electrical resistivity but it can form conductive surface layers when machined

59. Touch Resistance of Machined Parts: Machining may cause particle smearing on the surface and lead to formation of a conductive layer.

60. Resistance of this layer may depend on material type, machining method (grinding, milling, saw cutting etc.) and on machining direction.

61. Ferrotron 559H has very high touch resistance and does not form a conductive surface layer. No etching is required for this material except in cases when we expect relatively high voltage being applied to material (several hundred volts).

62. Fluxtrol 50 has good touch resistance (up to 30 k Ohms) on broken and machined surfaces but forms a thin conductive layer on side pressed surfaces. Etching is recommended for high frequency applications.

63. Fluxtrol A has very high internal resistivity but can easily form a conductive layer when machined. Machining of surfaces A and B causes much less conductive layers (if any) than of side surface C, where touch resistance may be as low as 10 – 30 Ohms. Etching is recommended in this case.

64. Guidelines for Fluxtrol Material Selection: Several factors must be taken into account in Fluxtrol material selection for particular applications:

65. Frequency range

66. Expected maximum voltage that may be applied to concentrator (required electric strength evaluation)

67. Coil style and geometry

68. Concentrator loading (required density B of magnetic field)

69. Duty cycle and heat transfer conditions

70. Prior experience and individual preferences

71. Frequency ranges of material overlap and two or even all three materials may be used for the same or similar application

72. All materials can work at frequencies lower than indicated in recommendations; for example Ferrotron 559 may be used at 10 kHz and even below

73. Low frequency materials may be used at frequency higher than specified if intensive cooling provided

74. This is a Fluxtrol Products General Selection Guide in terms of Coil Style, Frequency and Fluxtrol Material

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76. Here are selection guides for more coil styles.

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78. Fluxtrol Materials Application Technique

79. Fluxtrol Materials Application Technique

80. Etching: To Etch Or Not To Etch? That Is The Question!

81. Main Goal: To remove or modify conductive surface layer for better electrical resistance and electrical strength to applied voltage

82. Additional possible benefits:

- To prevent rusting

- To improve glue or coating adhesion

83. Disadvantage: Additional chemical operation

84. Recommendations: Etching is always useful but in majority of applications not required

85. Etching with Nitric or Chloric acids does not provide good results; it can damage material and the process is not safe

86. Phosphoric acid may be used with success for etching and rust prevention

87. Special iron-phosphoric agent CrysCoat 187 provides the bests results according to Fluxtrol Inc. experience

88. Contact Fluxtrol Inc. for more information

89. Machining: Fluxtrol materials may be machined using various methods (drilling, milling, turning, grinding, etc.)

90. No special tools required

91. It is not necessary to use cooling or lubricating liquids

92. General rules: Use sharp tools with slow feed and fast speed

93. When drilling pay attention to chips removal from the drill bit; clogged bit channels can result in material breaking or incorrect dimensions

94. Make pilot holes for drilling large bores

95. Drill material on strong support (wooden or plastic block) to avoid chipping at the exit

96. Fluxtrol A may give chipping on sharp edges due to layered structure. Machined surface may look different on different surfaces due to grain orientation.

97. Ferrotron 559H and Fluxtrol 50 may be machined into parts having sharp angles and thin (less than 1 mm) areas

98. Mechanical Properties of Fluxtrol materials: They are strong in compression, less strong in tension or bending loads

99. May be machined to any shape, drilled for coolant, quenchant supply or mechanical attachments

100. Threads may be cut directly in material for fastening

101. For example Fluxtrol 50 withstands a torque of 11 Nm when applied to a M8x8 bolt screwed directly into the material

102. Non-magnetic (brass or stainless steel) helicoils or other inserts are recommended for heavy mechanical loadings

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104. Fluxtrol Material Coating: Coating is not necessary for general applications

105. Some users apply paint or varnish for cosmetic reasons to concentrator together with the copper (whole coil) or separately

106. Ceramic coating can protect against electric contact to the work piece, magnetic chips and radiation from hot part. Coating may be applied to the whole coil face. Two layers (pre-coating and final) are the best

107. There are special requirements for a _clean_ environment in some high frequency high tech applications (semiconductor industry, food packaging etc.). Special coatings for these purposes are available (contact Fluxtrol Inc.). These coatings also increase electric strength of materials

108. Attachment Methods: Mechanical attachment using bolts is the most precise and reliable method. A thermally conductive agent is strongly recommended for use in-between Fluxtrol and the coil copper. For permanent installation use epoxy glue. A thermal conductive paste or silicone rubber may be used if ease of removal is required

109. Fasteners must be isolated from Fluxtrol concentrator when it is attached to multi-turn coil

110. Adhesive fastening Use a thermally conductive, high temperature resistant media. Epoxy composites with oxide or metal filler are the best. For thin layers (up to 0.2 mm) we recommend black Duralco 4525 epoxy from Cotronics. It is thin, has good adhesive properties and high temperature résistance. For thicker layers thicker epoxy compounds are recommended.

111. Use clean or copper-loaded silicone rubber for multi-turn coils to insulate controller from the coil turns. If controller overheats, use additional methods of temperature control (cooling plates, water spray, forced air)

112. Mechanical Attachment: Mechanical application of concentrator in combination with a thermally conductive adhesive is the most reliable method. If E-shaped concentrator is broken into two isolated C-shaped sections, no electrical insulation between coil tubing, studs and concentrator is necessary

113. For multi-turn coils it is necessary to insulate concentrator from turns and studs to avoid current leakage through the concentrator which can result in damage

114. Though controllers made of Ferrotron 119 or 559H can withstand applied voltage, electrical insulation is still recommended

115. Application Technique for Heavy Loaded Coils: Correct Application: Uniform gap 0.1-0.2 mm (5-10 mils) filled with thin layer of Duralco epoxy or similar material.

116. Incorrect Application Technique: Glue layer too thick.

117. Air Pockets.

118. Forced installation of material having insufficient clearance.

119. Example of Concentrator Application to Hairpin Coil: Possible concentrator failure due to metal chips on the face and significant voltage between copper legs

120. Ceramic coating and thin isolation sheet solve the problems

121. Methods of concentrator temperature control to prevent its overheating: Correct selection of material and its orientation

122. Correct selection of glue and concentrator application technique

123. Coil design with improved heat transfer from the concentrator material and reduced concentrator exposure to hot part surface

124. Intensive coil copper cooling; in short cycle applications copper may reach higher temperature than concentrator

125. Cooling plates

126. Ceramic coating of the coil surface

127. Additional cooling with quenchant, water channels, forced air etc.

128. In short-time static applications heat may be removed from the concentrator between the heating periods

129. Example of concentrator temperature control in heavy longitudinal scanning operation (seam annealing):

130. Magnetic flux density is higher in end areas (A) than in a regular zone resulting in higher material temperature. Copper side plates reduce 3D effects and provide additional heat transfer from the concentrator.

131. Example of concentrator temperature control in transversal scanning operation:

132. Chamfering of concentrator pole on the coil exit side reduces absorption of radiation from the heated part (right).

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134. Temperature Distribution in Fluxtrol Controllers: Typical temperature distribution in thickness of the concentrator pole for continuous regime.

135. Temperature distribution in glue layer (gray) and Fluxtrol pole (green).

136. Temperature differential in glue is too big (80 C). Adhesive must be thinner or more heat conductive.

137. In other applications temperature distribution may be strongly influenced by duty cycle, additional cooling on the external surface or radiation losses from the heated part.

138. This graph shows what would happen if we change the pole thickness with the same coil power.

139. For thinner pole magnetic flux density is higher but a path to a cold copper shorter and these factors compensate each other. However thermal resistance of glue layer remains the same and maximum temperature grows.

140. In this particular case the pole size reduction below 0.8 cm results in significant increase of Fluxtrol temperature.

141. Thermal Conductivity for Fluxtrol & Adhesive Materials: Max thermal conductivity of Fluxtrol A is close to that of stainless steel and is 5 times less in direction of pressing

142. Thermal conductivity of epoxy adhesives and compounds may vary in a wide range depending on glue and filler materials

143. Maintenance of Coils with Fluxtrol Concentrators: In many applications Fluxtrol concentrators can work longer than copper

144. Mechanical damage is one of the main factors causing coil failure and proper preventive measures must be taken

145. Visual control of Fluxtrol concentrators: Check concentrator integrity, attachment (loose parts, cracks in glue, mechanical damage) and insulation conditions when applicable

146. Periodically clean concentrator from metallic chips and scale

147. Restore damaged coating when applicable

148. Dark surface may be due to smoke and quenchant residue buildup. Gently scratch the surface with knife or other sharp tool. Cleaned surface must have grey metallic color typical for a particular type of material

149. Dark and crumbling surface shows that concentrator material was overheated. Concentrator must be replaced. If the coil lifetime is not sufficient, provide additional cooling or change the coil design

150. In some applications, especially in installations with tube generators, sparking from a concentrator to the part or fixture may occur. If there is a ground protection, the generator turns OFF quickly however there might be small areas on the concentrator damaged by sparking. Remove damaged volumes with a sharp tool and eliminate a factor that caused sparking (too small gap, metal particles etc.). Concentrator can continue to work if damage was small.

151. Examples of Applications

152. Examples of Applications

153. Mass Heating Inductor for Bending Operation: Heating of a beam with variable cross-section in a two-turn coil was non-uniform.

154. Local concentrators placed in strategic points solved the problem.

155. Mechanically fastened Fluxtrol A concentrators with fiberglass casings for better mechanical protection

156. Replacement of Laminations with Fluxtrol Materials: Fluxtrol A and 50 materials may be effectively used instead of laminations.

157. Their benefits are: Possibility to work at any frequency

158. Good performance in 3D fields resulting in longer lifetime of Fluxtrol concentrator compared to lams

159. Longer coil copper lifetime due to lower current concentration at the concentrator corners

160. Possibility to make controller of any geometry

161. Possibility of In-Field adjustment of concentrator to modify heat pattern

162. Much lower labor time and costs especially for complex geometries

163. Example: Laminations were initially applied to a single-short induction hardening coil working at 3 kHz.

164. Due to local overheating from 3-D field lams started to expand resulting in losing pattern; after 13,000 hits the coil completely failed (above).

165. Coil with Fluxtrol A concentrator produced over 50,000 hits and remained in working conditions.

166. C-shaped Concentrators Matching to Standard Copper Tubes: Netshape concentrators are designed for straight coil areas.

167. C-shape concentrators have optimal material orientation and dimensions that fit majority of standard tube sizes.

168. With small additional machining concentrators may be adjusted to fit more tube dimensions.

169. They may be used at low frequencies instead of laminations or at high frequencies where concentrators are not used at all (fastener heating etc.).

170. Application of these concentrators minimizes installation time and is very cost effective.

171. Brazing of Heavy Copper Bars for Nuclear Plants: Brazing of big copper bussbars for nuclear plants is a difficult task. Two inductors connected to the same power supply solved the problem. Application of Fluxtrol controllers to one of the coils provided balanced temperature distribution.

- Power 100 kW

- Frequency 10 kHz

172. Conclusions: Magnetic flux controllers made of Fluxtrol and Ferrotron materials are used in a large variety of induction applications ranging from soldering of small conductors at 2 MHz, to food packaging, to automotive parts heat treating, to melting of special materials and inductively coupled plasma

173. Due to unique combination of properties Fluxtrol materials are also used in electrophysics, material research and other special areas

174. Magnetic flux controllers improve heating quality, boost production rate and coil lifetime, save energy and manufacturing costs

175. Fluxtrol materials cover a whole frequency range of induction heating applications providing a variety of permeabilities from 7 to 120

176. Computer simulation gives a possibility to predict concentrator performance and optimize induction coil design

177. Correct application technique is essential for effective use of Fluxtrol controllers especially in heavy loaded cases

178. Fluxtrol Inc. provides extensive technical support to customers and continues to improve materials for magnetic flux control

179. This concludes this section. Thank you for viewing Fluxtrol Materials on Induction Coils

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