What causes the uneven support surface of the cylindrical head hexagon socket?

The unevenness of the hex socket support surface of the cylindrical head may be caused by  material issues, 

processing technology defects, improper clamping, tool problems, deformation during heat treatment, design or mold issues, etc. 

The following is a specific analysis: 

Material issue  Uneven material  : If the internal structure of the raw materials is unevenwith defects such as component segregation and inclusions, during the processing, the deformation resistance in different areas varies, 

which can easily lead to an uneven support surface. For instance, if the content of harmful elements such as sulfur and phosphorus in steel is too high,

 it will reduce the plasticity and toughness of the material. During cutting or cold heading, it is prone to uneven local deformation, causing the supporting surface to become uneven. 

Surface defects : If there are cracks, scratches, oxide scales and other defects on the material surface, when processing the hex socket support surface, 

these defects will affect the stability of the cutting, cause uneven force on the tool, and thus reduce the processing quality of the support surface. For instance, 

the oxide scale on the material surface may fall off during the cutting process, scratching the machined surface and causing unevenness. 

Processing Technology issues  Improper cutting parameters : During cutting processes such as turning and milling, if parameters like cutting speed, 

feed rate, and cutting depth are not properly selected, it will lead to unstable cutting force, thereby causing an uneven support surface. For instance,

 if the cutting speed is too high, it may accelerate tool wear, cause built-up edge and affect the roughness of the machined surface.

 Excessive feed rate will increase the cutting force, causing the workpiece to vibrate and resulting in ripples on the support surface. 

Cold heading process defects  : For cylindrical head hexagon socket bolts manufactured by cold heading process, if the cold heading die design is unreasonable or severely worn,

 it will lead to uneven metal flow, causing defects such as collapse and peeling on the support surface. For instance, if the cavity size of the cold heading die is inaccurate, 

it will cause the size of the hexagon socket support surface to exceed the tolerance and the surface to be uneven. 

 Grinding process issues  When grinding the hexagon socket support surface, if the grinding wheel is improperly selected, the grinding fluid is used unreasonably, 

or the grinding parameters are set incorrectly, it can lead to defects such as burning, cracking, and scratches on the grinding surface, affecting the flatness of the support surface.

 For instance, if the hardness of the grinding wheel is too high, it will cause burns on the grinding surface. Poor cooling effect of grinding fluid can cause thermal deformation of the workpiece 

and make the support surface uneven. 

Clamping issues  Uneven clamping force  : During the processing, if the clamping force distribution of the workpiece is uneven, 

it will cause elastic deformation of the workpiece. After processing, when the clamping force is removed, the workpiece will return to its original state, resulting in an uneven support surface.

For instance, when using a three-jaw chuck to clamp cylindrical workpieces, if the clamping force of the jaws is inconsistent, it will cause the workpiece to be eccentric, 

and the hexagon socket support surface processed will be inclined. Improper clamping method: An unreasonable clamping method may limit the freedom of the workpiece,

 causing it to vibrate or deform during the processing. For instance, when milling an Allen support surface, if the clamping position of the workpiece is inappropriate, 

it may cause the milling cutter to interfere with the workpiece during the processing, affecting the processing quality. 

Tool Issues Tool wear  As the processing proceeds, the tool gradually wears out, causing the cutting edge to become blunt and the cutting force to increase, which in turn leads to

 an increase in the surface roughness of the processed part and an uneven support surface. For instance, when a turning tool wears out, it will vibrate during cutting, 

causing ripples to appear on the supporting surface. 

 Unreasonable tool geometric parameters 

 The geometric parameters of the tool, such as the rake Anglerelief Angle, principal deflection Angle, and secondary deflection Angle, have a significant impact on the quality of the machined surface. If the geometric parameters of the cutting tool are not properly selected, it will lead to an unreasonable distribution of cutting force and a decline in the processing quality of the support surface. For instance, if the main deflection Angle is too small, 

it will increase the radial cutting force, causing the workpiece to vibrate and affecting the flatness of the supporting surface. Heat treatment issues 

Heat Treatment deformation

During the heat treatment process, the workpiece will generate thermal stress and organizational stress. If the heat treatment process is improper, such as too fast heating rate or uneven cooling,

 it will cause the workpiece to deform, making the hex socket support surface uneven. For instance, if the cooling rate during quenching is too fast, it will cause significant internal stress in the workpiece,

 leading to deformation of the workpiece and warping of the supporting surface. Residual stress: Residual stress will exist inside the workpiece after heat treatment. If the residual stress is too large,

 it will be released during subsequent processing or use, causing the workpiece to deform and making the support surface uneven. 

Design or mold issues  Unreasonable design 

If the design size, shape or tolerance requirements of the hex socket support surface are unreasonable, it will cause difficulties in processing and make it difficult for the support surface to

 achieve the designed flatness. For instance, if the depth of the Allen socket is too deep or the Angle is too small, it will make it difficult for the processing tool to reach the designated position,

 affecting the processing quality. 

Mold wear or damage  For hex socket support surfaces processed by molds, such as stamping and forging processes, if the mold is severely worn or 

damaged, it will lead to dimensional deviations and uneven surfaces of the processed support surfaces. For instance, when the cavity of the stamping die wears out, the edge of the hexagon

 socket support surface stamped out will be uneven and have burrs on the surface.