U.S. drill bit manufacturers are shifting to steel-based products to cut costs as tungsten prices surge due to trade restrictions and tighter supplies. North American producers are expected to ramp up drilling as disruptions to Middle Eastern oil supplies keep crude above $100 a barrel. But higher drill bit and equipment costs are raising the price of new wells, potentially slowing output growth at a time when global markets are counting on more U.S. supply. Drill bits, the cutting tools used to bore oil and gas wells, come in several types. Polycrystalline diamond compact (PDC) bits are typically made with either steel bodies or tungsten-heavy designs suited to tougher conditions. Tungsten is more durable and can account for up to 75% of materials in some oilfield drill bits. Prices for tungsten have jumped to about $3,000 per metric ton from around $600 in October following Chinese export curbs, supply tightening and stronger military demand. In response, manufacturers are increasing production of steel-body drill bits to contain costs.