DIN 988 Shim Rings — Carbon Steel, Bare (Uncoated)

FULLERKREG DIN 988 carbon steel bare shim rings are precision-stamped from carbon steel strip with no surface coating (bare / bright finish). Conforming to DIN 988, these thin flat rings are used for precise axial adjustment of bearings, shafts, and mechanical assemblies — setting bearing preload, eliminating axial play, and achieving precise dimensional tolerances in rotating machinery and gearboxes.

The bare (uncoated) finish provides the tightest dimensional control with no coating thickness variation, making these shims ideal for precision machinery, tooling, and dry or oil-lubricated environments where corrosion is not a concern. Multiple standard thicknesses (0.1–3.0 mm) can be stacked to achieve any required dimension.

Product Specifications

Standard	DIN 988
Material	Carbon Steel (low carbon, cold-rolled strip)
Surface Finish	Bare / Bright (uncoated, no plating)
Inner Diameter Range	Ø3 – Ø200 mm (larger on request)
Standard Thicknesses	0.1 / 0.2 / 0.3 / 0.5 / 1.0 / 2.0 / 3.0 mm
Thickness Tolerance	±0.010 mm (s≤0.5 mm) | ±0.015 mm (s>0.5 mm)
ID / OD Tolerance	H11 / h11 per DIN 988
Hardness	~120–160 HV (cold-rolled carbon steel)
Tensile Strength	~370–500 MPa
Temperature Range	Up to +200°C (dry) | Higher with lubrication
Density	7.85 g/cm³
Magnetic	Yes
Corrosion Resistance	Low — apply oil or grease for storage and use in dry/lubricated environments
Stacking	Multiple shims may be stacked
Related Standard	DIN 988 | ISO 3069

Product Gallery

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Dimensions — DIN 988 Full Range

d = inner Ø (H11) | D = outer Ø (h11) | s = available thicknesses (mm). Dimensions identical for all DIN 988 materials.

d (mm)	D (mm)	s (mm)
3	6	0.1/0.2/0.3/0.5/1.0
4	7	0.1/0.2/0.3/0.5/1.0
5	8	0.1/0.2/0.3/0.5/1.0
6	10	0.1/0.2/0.3/0.5/1.0
7	11	0.1/0.2/0.3/0.5/1.0
8	12	0.1/0.2/0.3/0.5/1.0
9	14	0.1/0.2/0.3/0.5/1.0
10	16	0.1/0.2/0.3/0.5/1.0/2.0
11	17	0.1/0.2/0.3/0.5/1.0/2.0
12	18	0.1/0.2/0.3/0.5/1.0/2.0
13	20	0.1/0.2/0.3/0.5/1.0/2.0
14	20	0.1/0.2/0.3/0.5/1.0/2.0
15	21	0.1/0.2/0.3/0.5/1.0/2.0
16	22	0.1/0.2/0.3/0.5/1.0/2.0
17	24	0.1/0.2/0.3/0.5/1.0/2.0
18	25	0.1/0.2/0.3/0.5/1.0/2.0
19	26	0.1/0.2/0.3/0.5/1.0/2.0
20	28	0.1/0.2/0.3/0.5/1.0/2.0
21	29	0.1/0.2/0.3/0.5/1.0/2.0
22	30	0.1/0.2/0.3/0.5/1.0/2.0
24	32	0.1/0.2/0.3/0.5/1.0/2.0
25	33	0.1/0.2/0.3/0.5/1.0/2.0
26	34	0.1/0.2/0.3/0.5/1.0/2.0
28	37	0.1/0.2/0.3/0.5/1.0/2.0
30	40	0.1/0.2/0.3/0.5/1.0/2.0/3.0
32	42	0.1/0.2/0.3/0.5/1.0/2.0/3.0
35	45	0.1/0.2/0.3/0.5/1.0/2.0/3.0
38	50	0.1/0.2/0.3/0.5/1.0/2.0/3.0
40	52	0.1/0.2/0.3/0.5/1.0/2.0/3.0
42	55	0.1/0.2/0.3/0.5/1.0/2.0/3.0
45	58	0.1/0.2/0.3/0.5/1.0/2.0/3.0
48	62	0.1/0.2/0.3/0.5/1.0/2.0/3.0
50	62	0.1/0.2/0.3/0.5/1.0/2.0/3.0
52	65	0.1/0.2/0.3/0.5/1.0/2.0/3.0
55	68	0.1/0.2/0.3/0.5/1.0/2.0/3.0
58	72	0.1/0.2/0.3/0.5/1.0/2.0/3.0
60	75	0.1/0.2/0.3/0.5/1.0/2.0/3.0
62	78	0.1/0.2/0.3/0.5/1.0/2.0/3.0
65	80	0.1/0.2/0.3/0.5/1.0/2.0/3.0
68	85	0.1/0.2/0.3/0.5/1.0/2.0/3.0
70	85	0.1/0.2/0.3/0.5/1.0/2.0/3.0
72	90	0.1/0.2/0.3/0.5/1.0/2.0/3.0
75	90	0.1/0.2/0.3/0.5/1.0/2.0/3.0
78	95	0.1/0.2/0.3/0.5/1.0/2.0/3.0
80	96	0.1/0.2/0.3/0.5/1.0/2.0/3.0
85	100	0.1/0.2/0.3/0.5/1.0/2.0/3.0
90	106	0.1/0.2/0.3/0.5/1.0/2.0/3.0
95	110	0.1/0.2/0.3/0.5/1.0/2.0/3.0
100	118	0.1/0.2/0.3/0.5/1.0/2.0/3.0
105	123	0.1/0.2/0.3/0.5/1.0/2.0/3.0
110	130	0.1/0.2/0.3/0.5/1.0/2.0/3.0
115	135	0.1/0.2/0.3/0.5/1.0/2.0/3.0
120	140	0.1/0.2/0.3/0.5/1.0/2.0/3.0
125	145	0.1/0.2/0.3/0.5/1.0/2.0/3.0
130	152	0.1/0.2/0.3/0.5/1.0/2.0/3.0
135	158	0.1/0.2/0.3/0.5/1.0/2.0/3.0
140	162	0.1/0.2/0.3/0.5/1.0/2.0/3.0
145	168	0.1/0.2/0.3/0.5/1.0/2.0/3.0
150	172	0.1/0.2/0.3/0.5/1.0/2.0/3.0
155	178	0.1/0.2/0.3/0.5/1.0/2.0/3.0
160	185	0.1/0.2/0.3/0.5/1.0/2.0/3.0
165	190	0.1/0.2/0.3/0.5/1.0/2.0/3.0
170	195	0.1/0.2/0.3/0.5/1.0/2.0/3.0
175	200	0.1/0.2/0.3/0.5/1.0/2.0/3.0
180	206	0.1/0.2/0.3/0.5/1.0/2.0/3.0
185	212	0.1/0.2/0.3/0.5/1.0/2.0/3.0
190	216	0.1/0.2/0.3/0.5/1.0/2.0/3.0
195	222	0.1/0.2/0.3/0.5/1.0/2.0/3.0
200	228	0.1/0.2/0.3/0.5/1.0/2.0/3.0

Contact FULLERKREG for non-standard sizes or sizes above Ø200 mm.

Carbon Steel Bare vs A2 Stainless — Material Selection Guide

Property	Carbon Steel Bare (This Product)	A2 Stainless (SUS304)
Corrosion resistance	Low — oil/grease required	Good — no coating needed
Dimensional accuracy	Highest — no coating variation	High — passivation film negligible
Cost	Low	Medium–high
Magnetic	Yes	Slightly (after cold working)
Best for	Oil-lubricated gearboxes, sealed machinery, tooling	Food, pharma, corrosive environments

Typical Applications

• ⚙️ Bearing preload & axial adjustment — angular contact, tapered roller, and thrust bearings in gearboxes and spindles
• 🔧 Shaft spacing & gear positioning — precise axial positioning of gears, pulleys, and sprockets in oil-lubricated assemblies
• 🏭 Gearbox & transmission assembly — automotive and industrial gearboxes, differentials, and transmission assemblies
• 🤖 CNC & precision machinery — spindle bearing preload in machining centres and grinding machines
• 🚗 Automotive & motorsport — differential bearing preload, gearbox shaft positioning, engine assembly
• 🛠️ Tooling & fixtures — precise height adjustment in machining fixtures, jigs, and precision tooling
• 📦 General industrial machinery — cost-effective shim solution for sealed or oil-wetted mechanical assemblies

FAQ

Q: What does "bare" surface finish mean?
A: Bare means the shim ring has no surface coating, plating, or treatment — it is the raw cold-rolled carbon steel strip as stamped. This provides the tightest dimensional control with no coating thickness variation. Bare carbon steel shims should be stored and used in dry or oil-lubricated environments to prevent rust.

Q: How do I prevent rust on bare carbon steel shims?
A: Apply a light coat of machine oil or anti-rust oil before storage and assembly. In oil-lubricated gearboxes and sealed assemblies, the lubricant provides sufficient protection. For environments with moisture exposure, specify A2 stainless steel shims instead.

Q: How do I select the correct thickness?
A: Measure the axial gap with a dial gauge. Required shim = measured gap − target clearance. Combine standard thicknesses (0.1, 0.2, 0.3, 0.5, 1.0, 2.0, 3.0 mm) to achieve the exact value. Verify each shim with a calibrated micrometer before assembly.

Q: Can I stack multiple shims?
A: Yes. Total stack = sum of individual shims. Ensure all shims are clean, flat, and burr-free before assembly.

Q: What is the difference between DIN 988 shim rings and DIN 125A flat washers?
A: DIN 988 shim rings are precision components with tight thickness tolerances (±0.010–0.015 mm) for axial adjustment in precision machinery. DIN 125A flat washers are general-purpose load distribution washers with much looser tolerances. They serve entirely different engineering functions.