High-Quiet Rubber Cover of Sandvik HLX5T Rock Drill in Russia

The HLX5T is a louder drill than development drifters by design—its heavier percussion energy class and higher pressure operation produce a higher sound power level at the piston strike event. In sublevel caving production at Polyus Gold's Blagodatnoye gold mine in Krasnoyarsk Krai—where HLX5T rigs drill production fan holes in highly competent Archaean gneiss and amphibolite at 180–210 MPa—the drill operator is stationed 8–12 meters from the drifter in the drilling drive while the rig drills automatically. The rubber covers that wrap the percussion cylinder housing, flushing device, and rear housing are the primary passive noise reduction measure at the rig itself, complementing the operator cab's acoustic isolation.

The rubber cover's noise attenuation comes from two mechanisms: mass-damping (the rubber adds mass to the percussion cylinder's outer surface, reducing the vibration amplitude at the radiated frequency) and acoustic absorption (the open-cell foam backing inside the cover absorbs sound energy rather than reflecting it). The quality metric is insertion loss—the difference in dB(A) at the operator position with and without the covers installed. New covers on an HLX5T at Blagodatnoye produce 4–6 dB(A) insertion loss; worn, cracked, or compressed covers with lost foam structure produce 1–2 dB(A). That 3–4 dB(A) difference is the margin between a compliant and non-compliant operator exposure level at the Russian 80 dB(A) regulatory threshold.

Rubber Cover Condition and Noise Performance at Blagodatnoye

Polyus Gold's Blagodatnoye production drill supervisors perform a rubber cover condition check at each 500-hour service—compressing the cover with thumb pressure to check foam resilience and inspecting the full surface for cracks. Any cover showing foam collapse or cracks wider than 2 mm is replaced before the rig returns to service. HOVOO supplies HLX5T rubber cover sets for Russian production drill operations. References at hovooseal.com.