When selecting linear guide rails, the first step is to determine the rail width. Numbers like 15, 20, 25, 30, 35, 45, 55, 65 represent the nominal size of the slider and are the starting point of selection. Choose too small and rigidity suffers; choose too large and you waste space and budget. Today, let's talk about the selection logic for HGH series sliders, from size 15 to 65 – all based on practical experience I've gathered over the years.
1. Size Range: From 15 to 65, Covering Most Applications
The HGH series is a high‑profile square slider from Zhejiang Baili Guide Rail. It shares the same rail as the HGW flange‑type slider, but the slider shape is different – HGH is square with threaded blind holes, suitable for mounting worktables from the side or top.
Common sizes include 15, 20, 25, 30, 35, 45, 55, and 65, covering everything from small precision equipment to heavy‑duty machine tools. The larger the size, the longer the slider, the more balls it contains, and the higher its load capacity and rigidity. For example, the HGH15CA has an overall height of only 28mm, suitable for small automation equipment; while the HGH65CA has an overall height of 90mm and a rated dynamic load of up to 208.36kN, capable of handling loads of several tens of tons. The weight of HGH series sliders ranges from 0.18kg (size 15) to 9.82kg (size 65), so the impact on moving mass should also be considered during selection.
2. When to Choose Small Sizes (15/20/25) and When to Choose Large Sizes (45/55/65)?
Small sizes (15/20/25): Suitable for light loads, high speed, and short stroke. Examples: 3D printers, small engraving machines, electronic assembly equipment, medical diagnostic instruments. These applications are weight‑sensitive – the lighter the slider, the better. Speed and acceleration are high, loads are low, and small sizes are sufficient. For a 3D printer's X/Y axis, HGH15 or HGH20 is more than enough; using size 35 would increase moving inertia and reduce print speed.
Medium sizes (30/35): The most commonly used sizes, balancing rigidity and speed. General CNC engraving machines, small to medium automation lines, packaging machinery, woodworking equipment – sizes 30 and 35 are mainstream choices. For a 1325 engraving machine, HGH30 on the X‑axis and HGH25 or HGH30 on the Y‑axis is a typical configuration. It ensures adequate rigidity while keeping cost under control.
Large sizes (45/55/65): Suitable for heavy loads and high rigidity requirements. Large gantry mills, heavy‑duty cutting machine tools, automotive parts production lines, stone cutting machines – these need to handle several tons or even tens of tons of load, demanding extremely high rail rigidity and vibration resistance. Small sizes simply can't cope. A large gantry mill's X‑axis requires at least HGH45 or even HGH55. One customer used HGH65 on a heavy‑duty cutting machine and it has run without issues for years.
3. Four Key Parameters for Selection
1. Accuracy grade
The HGH series offers five accuracy grades: Normal (C), High (H), Precision (P), Super Precision (SP), and Ultra‑High Precision (UP). Normal is for general automation handling; High is for general CNC; Precision and above are for precision machining centers and grinders. Selection principle: the higher the machine's accuracy requirement, the higher the accuracy grade needed. If the machine has a linear scale for closed‑loop control, you can go one grade lower.
2. Preload grade
Preload options: Z0 (no preload), ZA (light preload), ZB (medium preload). Z0 is for light loads and low friction; ZA is for general positioning with moderate rigidity; ZB is for heavy cutting and impact loads. Higher preload gives better rigidity but increases friction and heat. For high‑speed machines, choose lower preload; for heavy cutting, choose higher preload. My rule of thumb: when in doubt, pick ZA – it works for most conditions.
3. Slider type
The HGH series includes standard (CA) and long (HA) types. The long slider is longer, contains more balls, and offers 30‑50% higher load capacity and rigidity than the standard type. It is suitable for cantilever structures or heavy load applications. The HGH20HA is noticeably longer than the HGH20CA, and their mounting hole spacing differs. If installation space allows, prioritise the long type for better rigidity.
4. Mounting hole spacing
Different size sliders have different mounting hole spacing. When changing sizes, always re‑check the threaded hole positions on your slide table. The HGH15CA uses M4 or M5 screws, while the HGH65CA uses M16 screws – a huge difference. Always verify the drawings before ordering, so you don't end up with parts that won't fit.
4. Typical Applications by Size
| Size | Overall Height (mm) | Slider Length (mm) | Typical Applications |
|---|---|---|---|
| HGH15 | 28 | ~60 | 3D printers, small engravers, medical equipment, electronic assembly |
| HGH20 | 30 | ~70 | Small CNC, automation modules, packaging machinery, laser markers |
| HGH25 | 40 | ~84 | General engravers, small to medium automation lines, woodworking |
| HGH30 | 45 | ~98 | CNC machining centres, medium automation equipment, measuring instruments |
| HGH35 | 55 | ~112 | Heavy‑cutting machine tools, gantry mills, precision machining |
| HGH45 | 70 | ~139 | Large gantry mills, heavy automation lines, automotive parts equipment |
| HGH55 | 80 | ~160 | Large machining centres, heavy‑duty cutting, stone cutting machines |
| HGH65 | 90 | ~203 | Ultra‑heavy equipment, large gantry mills, shipbuilding machinery |
Data reference: HGH20CA slider length ~70mm, HGH45CA ~139mm, HGH65CA ~203mm.
5. Easily Overlooked Points in Selection
1. Rails longer than 4 metres require joining
Most standard rails have a maximum length of 4 metres. If the stroke exceeds 4 metres, two rails must be joined. The ends must be ground flat and the raceways aligned, which increases installation difficulty. For strokes over 3.5 metres, consider whether such a long stroke is really necessary, or switch to rack‑and‑pinion drive.
2. More sliders is not always better
Two sliders per rail is the most common configuration. Using three or four sliders demands extremely high base flatness – any slight error will cause the sliders to fight each other, increasing resistance and reducing life. Unless the load is exceptionally high or the stroke very long, two sliders are sufficient.
3. Don't skimp on dust protection
HGH series sliders have end seals and side wipers, and contain grease internally, offering decent dust protection. In dusty environments, however, standard seals are not enough – you must add dust covers. Woodworking, stone cutting, and welding equipment will destroy rails quickly without dust covers.
4. Lubrication intervals depend on operating conditions
HGH sliders have internal grease reservoirs, but lubrication intervals cannot be one‑size‑fits‑all. High‑frequency machines need shorter intervals; low‑frequency machines can go longer. My practice: for continuously running machines, grease every 500‑800 km of travel; for intermittent operation, check every 3‑6 months. Too little grease accelerates wear; too much attracts dust – find the right balance.
6. A Few Honest Words
The HGH series slider, from size 15 to 65, covers the vast majority of applications – from small precision equipment to heavy‑duty machine tools. When selecting, don't just think "bigger is better". Calculate the load, check the space, define the accuracy – choose the most suitable size, not the most expensive.
Zhejiang Baili Guide Rail offers the full HGH series, sizes 15 to 65, in both standard and long types, with multiple accuracy and preload options. If you're unsure which size fits your machine, send us your load parameters and mounting drawings – we'll help you calculate.
