How are motor laminations firmly fixed together? What are the “hardcore” technologies? In fact, there is more than one motor core lamination stacking methods! Common techniques include bonding, welding, interlocking, riveting, bolting, and clamping.
Want to know which stacking technology suits your motor best? Keep reading!
Electric Motor Core Lamination Stacking Methods
Bonded Electric Motor Lamination
The glue bonding and self-bonding technologies for electric motor cores have emerged as innovative fixing methods in recent years. Both techniques achieve motor core fixation by applying a special adhesive between laminations.
Adhesive bonding can withstand temperatures up to 180°C, with a thickness of only 2μm.
What is “Dot Gluing Bonding Technology“?
As the name suggests, when bonding rotor and stator stacks, small adhesive dots are applied to the laminations. Before the adhesive cures, a fixture applies appropriate pressure to the core to ensure tight adhesion and prevent misalignment. The core is then placed in a curing oven for high-temperature curing.
With technological advancements, more suppliers are using continuous in-mold dot gluing to achieve mass production of motor cores. Tesla’s Model 3 currently adopts this process.
What is “Self-Bonding Technology“?
Self-bonding motor cores involve pre-coating both sides of the electrical steel laminations with a bonding varnish material. The silicon steel sheets, coated with adhesive, are stacked in a predetermined order and direction.
After stacking is completed, the core is cured by heating to form a stable bonding layer that permanently fixes the silicon steel sheets together.
What Materials Are Used for Bonding Laminations?
EB549
Magna-Tac E645
Magna-Tac F310
MX-6272
Magna-Tac TR-8899
Although bonded motor cores offer better performance and lower eddy current loss, most customers opt for welding technology due to cost considerations.
Welded Lamination
Welding methods for motor cores mainly include laser welding, TIG welding, MIG welding, and spot welding. The primary difference lies in the heat source used for fusion welding, including laser, electron beam, plasma arc, and electric arc (TIG, GTA, CMT).
Traditional manual arc welding is rarely used due to its low arc heat, large heat-affected zone, rough welds, lack of automation, and low efficiency.
Tungsten inert gas (TIG) welding is widely used because of its stable arc length, good arc elasticity, no need for filler metal, easy control of welding parameters, smooth and clean welds, and minimal spatter. However, due to the high silicon content in silicon steel sheets, their weldability is poor, leading to cracking after welding and high welding difficulty.
In recent years, laser welding has become a promising alternative. This method primarily welds several axial seams along the outer circumference of the stator, firmly joining the silicon steel sheets.
Laser welding focuses a high-power-density laser beam into a small spot, concentrating energy with high density and rapid heating efficiency, thus minimizing metal deformation.
Interlocked Motor Stator and Rotor Lamination
This method is commonly used in continuously the mass production of stamped motor cores. Certain geometric shapes, known as interlocking points, are punched into the rotor and stator laminations at appropriate positions.
The interlocking process inside the mold involves the following: At the blanking station, the raised interlocking point on the upper lamination precisely aligns with the recess on the lower lamination. When the upper lamination is pressed by the blanking punch, the reaction force from the lower lamination and the die wall causes the two laminations to interlock.
What Are the Different Shapes of Interlocking Points?
Square or Circular Interlocking Points: High positioning accuracy, minimal space requirement, enabling interlocking in tight spaces. Lower interlocking force, requiring high-precision molds.
V-Shaped Riveting Points: Allows for slight skewing of the stacked laminations. Provides higher interlocking force and easy alignment of riveting positions.
L-Shaped Riveting Points
Trapezoidal Riveting Points
Riveted Lamination Stacks
This riveting technique is primarily used for motor laminations produced via laser cutting, wire cutting, or compound stamping. Circular holes are cut or stamped at appropriate positions on the stator or rotor laminations. The laminations are then fixed in place using fixtures, and rivets, bolts, or other fasteners secure them together.
The circular holes in motor laminations can be threaded or non-threaded through-holes. Rivets are classified as head rivets and flat rivets. Riveting can be performed manually or with a riveting machine.
The principle of bolting is the same as that of riveting.
Cleating Stator Lamination
These cores are assembled by pressing steel strips into grooves around the outer perimeter of the laminations. The cleating strips are usually galvanized or cold-rolled (CR) strips, with thicknesses up to 2mm. There are two buckle methods: straight and oblique. Each stator contains 2 to 16 clamping grooves.
The positions of the clamping grooves should align with the stator teeth or slots, preferably with the stator teeth. For large stators with multiple clamps, they must be evenly distributed around the stator’s perimeter, always in pairs, spaced 18 degrees apart.
The stacking method of motor laminations directly affects motor performance and manufacturing costs.
Different laminate stacking methods offer distinct advantages in structural strength, electromagnetic performance, and assembly processes.
The most suitable method should be chosen based on the motor’s application scenario to ensure efficiency, stability, and longevity.
Motor Lamination Bonding and Stacking – Choose Lamnow
As a professional generator and motor core manufacturer, Lamnow has extensive production experience and can process stator and rotor cores using various stacking methods based on customer needs. Our electrical motor lamination is widely used in automotive, electric vehicles, aerospace, and power tools.
If you have specific project requirements, feel free to provide drawings, and our engineering team will evaluate and recommend the optimal manufacturing solution. Contact us anytime for professional support!
