Method of setting mold clamping force of injection molding machine

A method of setting a mold clamping force of an injection molding machine that sets a mold clamping force smaller than a maximum mold clamping force when a mold is clamped by a mold clamping device,

• wherein test molding is performed by sequentially clamping the mold with a mold clamping force obtained by sequentially lowering a mold clamping force by a predetermined amount from the maximum mold clamping force;
• and, when a mold clamping pressure in an injection process is detected with a mold clamping pressure sensor and a plurality of different monitored elements corresponding to a variation of the mold clamping pressure are monitored, wherein the plurality of different monitored elements include at least two of the mold clamping pressure differential value of the mold clamping pressure with respect to time and a reduction rate of the mold clamping pressure with respect to time, and thus it is detected that at least one of the monitored elements is varied to exceed a predetermined threshold, a mold clamping force obtained by increasing a mold clamping force at a time of production of the variation by a predetermined amount is set as a proper mold clamping force.