Projections (low thermal mass islands) are one method of insuring proper heat balance in difficult spot welding applications when there exists a 5:1 size difference between the parts to be welded. By providing a projection on the surface of one of the workpieces, weld current and force can be focused into the small area of the projection to produce heat at the desired weld location. Projection welding can extend electrode life by increasing the electrode contact area and decreasing the current density at the surface of the electrode. Projection welding is effective even if the weldments are thick. For more information regarding designing projections, see our blogs '凸焊：平衡热量并延长电极寿命”和“为气密密封装设备设计环状突起元件。”'