apparatus for the rapid removal of burrs from workpieces by the application of transient thermal energy in a closed chamber . the chamber comprises a downwardly open upper closure fixedly supported above a vertically movable lower closure , both closures being water - cooled . means are provided for alternately moving work supporting platens into position above the retracted lower closure . after being raised by a yieldable motor , the lower closure is drawn into sealing contact with the upper closure by a plurality of screws mounted around the upper closure and supporting a clamping ring . pressure tightness is achieved by an uncompensated seal which does not require excessive clamping forces . combustible gases are metered to the chamber and at the same time to charging cylinders , the gases in the charged cylinders then being forced into the chamber to obtain the maximum gas charge . the mixture passes through a mixing block having poppet valves which open in a downstream direction and are thus aided in closing by the explosive force . a controlled amount of water is also injected into the mixing block to protect these valves . an exhaust valve is provided in the mixing block so that the spent gases do not flow past and cause damage to the chamber seal when the lower closure is opened .