Overview
The half-countersunk head bolt, also known as a 'button head' or 'low-profile countersunk' bolt, is a versatile fastener designed for applications where a protruding bolt head is undesirable but full countersinking isn't required. These bolts feature a flat top surface with a conical underside that tapers to the shank, allowing partial recessing into materials while maintaining higher shear strength than fully countersunk alternatives. Widely standardized under DIN 7991 and ISO 10642, these bolts are particularly valued in industries where aerodynamics, safety, or aesthetics matter. The design reduces snag hazards and creates smoother surfaces compared to standard hex bolts, making them ideal for moving parts or visible assemblies.
Structure and Working Principle
A half-countersunk bolt's geometry includes three critical elements: the flat bearing surface (typically with a Phillips or slot drive), the conical transition section (usually at a 90° angle), and the threaded shank. The partial countersink allows approximately 50-60% of the head height to sit above the material surface while distributing clamp load effectively. When installed, the conical section compresses against the material as torque is applied, creating both axial clamping force and radial friction that resists loosening. This design offers better vibration resistance than flat head screws while maintaining lower profile than hex bolts. The drive style (commonly slot or Phillips) allows for tool engagement even when partially recessed.
Key Features
Material versatility is a hallmark of half-countersunk bolts, with common options including grade 8.8 carbon steel for general use, A2/A4 stainless steel for corrosion resistance, and alloy steel for high-strength applications. Surface treatments range from zinc plating to hot-dip galvanizing, chosen based on environmental exposure. The bolts' dimensional precision ensures consistent performance, with head diameters typically 1.5-2 times the shank diameter. Unlike fully countersunk bolts, these maintain sufficient head height for reliable tool engagement even after years of service. Their hybrid design makes them particularly useful when mating with both countersunk and non-countersunk holes in assemblies.
Application Areas
Automotive manufacturing frequently employs half-countersunk bolts for body panels, interior trim, and undercarriage components where road debris clearance matters. Their streamlined profile reduces air turbulence in moving vehicles while providing secure fastening for vibration-prone areas. In industrial machinery, these bolts secure guards, covers, and access panels that require frequent removal. The construction industry uses them for metal framing, cladding systems, and architectural metalwork where both strength and finish quality are priorities. Electronics manufacturers value them for chassis assembly where space constraints prohibit protruding fasteners.
Maintenance and Precautions
Regular inspection should check for signs of thread wear, corrosion (especially in stainless steel variants), and proper seating. Unlike standard bolts, partially countersunk heads can trap moisture against the conical surface, making proper material selection critical for outdoor applications. When installing, ensure pilot holes match the bolt's major diameter to prevent material splitting. Use calibrated torque tools to avoid over-tightening, which can distort the countersink. For critical applications, consider thread-locking compounds or nylon-insert nuts to prevent vibration-induced loosening. Always match bolt material to mating components to prevent galvanic corrosion.
B2B Procurement Guide
Industrial buyers should specify material grade, surface treatment, and drive type (slotted, Phillips, or Torx) when ordering. Bulk purchases (typically 1,000+ units) commonly offer 15-30% cost savings. Leading manufacturers include Fastenal, Bossard, and specialized Asian suppliers for high-volume needs. Quality verification should include checking for ISO 898-1 compliance on mechanical properties and salt spray test results for corrosion-resistant coatings. For customized orders, lead times typically range from 4-8 weeks. Just-in-time procurement is feasible for standard sizes stocked by industrial distributors, with MOQs as low as 100 pieces for common variants.
Related Manufacturers
- 主营：预埋钢板、焊钉、大六角钢结构连接副、钢结构扭剪型螺栓、钢结构大六角螺栓、厂房钢结构大六角螺栓、桥梁大六角高强度螺栓、摩擦型大六角螺栓、扭剪型高强度螺栓、10.9级扭剪螺栓、扭剪型钢结构螺栓、扭剪螺栓连接副、剪力栓钉、圆柱头焊钉、钢结构剪力钉、栓钉连接件、桥梁焊钉、楼承板栓钉、磁环焊钉、钢结构预埋板、预埋铁板、镀锌预埋板、栓钉、剪力钉、焊接预埋钢板
- 主营：[]
- 主营：缩梗螺栓、扭剪螺栓、双头螺栓、预埋螺栓、大六角螺栓、高强度螺栓、双头螺纹螺栓、地脚螺栓、预埋件、全螺纹螺柱
- 主营：热镀锌螺丝、热镀锌连接副、锚栓、钢结构大六角螺栓、钢结构扭剪型螺栓、热镀锌螺栓、热渗锌螺栓、热镀锌高强度螺栓、地脚螺栓、预埋地脚螺栓、地基锚固螺栓、大六角头螺栓、高强度大六角螺栓、10.9级扭剪型螺栓、扭剪型螺栓、扭剪型高强度螺栓、扭剪螺栓、国标热镀锌螺栓、风电螺栓、基础地脚螺丝、设备地脚锚栓、预埋锚栓、热镀锌紧固件
- 主营：自攻螺丝、燕尾螺钉、圆形弹垫、螺栓螺丝、六角螺栓、焊接螺栓、螺栓垫片、双头螺栓、注塑螺栓、自钻螺钉、螺母垫片、活节螺丝、六角螺母、法兰螺母、加大平垫、六角螺丝、法兰螺帽、化学锚栓、压板螺母、自钻螺丝、钻尾螺钉、拉铆螺母、导向螺钉、钻尾螺丝、螺丝螺母
- 主营：钢结构、混凝土、重载设备、地脚螺栓、预埋螺栓、预埋锚栓、地脚锚栓、大棚地锚、防护包装、地脚配件、地脚螺丝、螺母垫板、字型地脚丝、镀锌螺旋地锚、加长抗拔地锚、大棚基础地锚、农田围栏地锚、桥梁锚固地脚栓、两款热镀锌大棚
- 主营：[]
- 主营：[]
- 主营：组合螺栓、外六角螺栓、外六角组合件、外六角组合套装、外六角组合螺丝
- 主营：[]
- 主营：UNI意标紧固件、ANSI美标紧固件、GB国标紧固件、半沉头螺栓、DIN德标紧固件
- 主营：电力铁件、电力金具、拉线抱箍、铁塔螺栓、招弧角螺栓、镀锌支架、电缆支架、直线横担、电力支架、加强抱箍、光伏支架、电力瓷瓶、拉紧绝缘子、电镀锌方垫片、铁塔铁附件、陶瓷绝缘子、瓷瓶绝缘子、电力夹板、地锚拉环、卡盘抱箍、电缆s挂钩、双圈拉线棒、镀锌自功卡、热镀锌联板、光伏地桩
- 主营：六角螺栓、螺母、紧固件
- 主营：螺母、螺钉、垫圈、螺栓、铆钉、组合螺丝、自攻螺丝、钻尾螺丝、紧定螺丝、销轴、膨胀螺丝、螺柱、牙条、挡圈、机械零件、索具、螺丝钉、弹簧、车床加工
- 主营：楼梯护角、钢筋马镫、止水钢板、止水螺栓、穿墙螺栓定制、钢筋套筒定制
- 主营：4145H螺栓、头连接销
- 主营：旋钮按钮、阻尼缓冲器、塑料门扣、滚花尼龙螺栓、汽车卡扣、塑料铆钉
- 主营：高强度内六角螺栓厂家、抗震支架
- 主营：化学螺栓、预埋螺栓、钢结构螺栓
- 主营：弹簧扣、开口销、标准件、十字槽沉头螺钉、肩螺丝、斜垫圈、紧固件、自攻钉、斜垫片、安全螺母、两用扳手、六角螺母、防盗螺丝、止动垫圈、焊接螺母、蝶形螺丝、弓形卸扣、自攻螺钉、十字螺钉、焊接螺钉、钢丝螺套、手拧螺丝、开槽螺钉、皇冠螺钉、法兰螺丝、喉箍挂件
- 主营：螺母、光伏、热镀锌、螺栓、高强度、光伏配件
- 主营：a286螺丝、310s螺丝、c276螺丝、inconel718螺栓、进口螺丝、耐高温螺丝、外六角螺丝、内六角螺丝、astma193b8螺柱、inconel718螺丝、耐热不锈钢螺丝
- 主营：预埋件、焊接螺丝、厂房电力铁塔、地脚螺栓、羊眼螺栓、不锈钢薄螺母、镀铜焊接螺母、防松螺母、高强度螺母、家具锥形螺母、卡式螺母、盲孔压铆螺母螺柱、内外牙螺母、热镀锌螺母、台阶螺母、四爪螺母、外六角钻尾螺丝、304不锈钢喉箍、T型螺丝、不锈钢方形卡箍、T型螺母、法兰带垫螺母、马车螺丝、外六角内膨胀螺丝、不锈钢弹垫垫圈
- 主营：10.9S钢结构螺栓、Q235B地脚螺栓、8.8级高强度外六角、Q355B预埋锚栓、3米镀锌丝杆
- 主营：方u型卡、电缆挂钩、精轧垫板、u型螺栓、单头螺栓、9字地脚螺栓、高强度地脚螺栓、地脚螺栓、双头螺栓、异形钩子、预埋钢板、电缆支架、角钢支架、钻尾丝
- 主营：不锈钢螺栓、热镀锌螺栓、高强度螺栓、光伏配件