在溫擠壓前除了要對坯料進行加熱和潤滑外，還要對擠壓凸模和凹模進行預熱。一般預熱至150～300℃再進行擠壓生產。護坡模具預熱主要為了保證：
Before warm extrusion, in addition to heating and lubricating the blank, the extrusion punch and die should be preheated. Generally, it is preheated to 150-300 ℃ before extrusion. The preheating of slope protection mould is mainly to ensure that:
(1)使擠壓坯料放入模具時坯料降溫不致過快，以免塑性降低、變形抗力增加；同時避免坯料表面和中心層溫差過大，以防止由于變形不均勻性而導致擠壓件產生缺陷或護坡模具損壞。
(1) When the extruded blank is put into the mold, the temperature of the blank will not be too fast, so as to avoid the reduction of plasticity and the increase of deformation resistance; at the same time, the temperature difference between the surface of the blank and the central layer shall be avoided, so as to prevent the extrusion parts from producing defects or damage to the slope protection die due to the uneven deformation.
(2)減小護坡模具與毛坯接觸的溫差，避免模具表面的溫度迅速上升而導致護坡模具內部溫差過大而產生很大的內應力，以降低護坡模具在工作時產生破壞的危險。
(2) Reduce the temperature difference between the slope protection mold and the blank, avoid the rapid rise of the surface temperature of the mold, which leads to the large temperature difference inside the slope protection mold and produce great internal stress, so as to reduce the risk of damage of the slope protection mold in the work.
護坡模具預熱的具體方法是在模具上安裝專門的電阻預熱器，或用噴燈或在護坡模具上放置燒紅的鐵塊進行預熱，預熱溫度視擠壓毛坯溫度而定。
The specific method of preheating the slope protection mould is to install a special resistance preheater on the mold, or use a blowtorch or place a red iron block on the slope protection die for preheating. The preheating temperature depends on the temperature of the extruded blank.