Material deposition system for additive manufacturing

An additive manufacturing apparatus comprising:

• a build platform;
• an extruder movable relative to the build platform, the extruder defining a first input passage for receiving a first material in filament form, and a second input passage for receiving a second material in filament form;
• a first actuator configured to feed the first material in filament form at a first feed rate through the first input passage, and a second actuator configured to feed the second material in filament form at a second feed rate through the second input passage;
• one or more heaters located downstream of the first input passage and/or the second input passage, the one or more heaters being configured to heat and/or liquefy the first material and/or the second material;
• a chamber within the extruder for combining the first material and the second material to form a combined deposition material;
• a sleeve within the chamber, the sleeve being movable within the chamber between a first position and a second position to vary the exposure time of the second material with the first material based on the position of the sleeve within the chamber;
• a sleeve actuator operatively coupled to the sleeve, the sleeve actuator being configured to move the sleeve between the first position and the second position;
• an extrusion port for extruding the combined deposition material;
• and
• a controller operatively coupled to each of the first actuator, the second actuator, the sleeve actuator, the one or more heaters, and to the extruder;
• wherein the controller is configured to control the feed rates of the first actuator and the second actuator according to instructions from a computer model;
• wherein the controller is configured to control movement of the extruder relative to the build platform for depositing the combined deposition material according to the instructions from the computer model;
• and
• wherein the controller is configured to control the sleeve actuator to move the sleeve between the first position and the second position for controlling the exposure time of the second material with the first material according to the instructions from the computer model.