Dimensions & Tolerances

Investment casting, often used for the production of parts with high precision requirements, places great importance on the dimensions and tolerances of the cast parts. Dimensions and tolerances can vary depending on design requirements and specific applications. Below are a few examples that provide general information about the common dimensions and tolerances used in investment casting:

VDG P690 D1, D2 and D3 Tolerance Classes

VDG P690 Linear Tolerances (DCT)

Nominal size (mm)	D1	D2	D3
≤ 6	0.30	0.24	0.20
6 – 10	0.36	0.28	0.22
10 – 18	0.44	0.34	0.28
18 – 30	0.52	0.40	0.34
30 – 50	0.80	0.62	0.50
50 – 80	0.90	0.74	0.60
80 – 120	1.10	0.88	0.70
120 – 180	1.60	1.30	1.00
180 – 250	2.40	1.90	1.50
250 – 315	2.60	2.20	1.60
315 – 400	3.60	2.80	–
400 – 500	4.00	3.20	–

Values apply to steel, stainless steel and similar alloys (material group D) and show the total tolerance field. For example, 0.30 mm placed symmetrically means ±0.15 mm. D3 applies to individual dimensions by agreement with the foundry.

Angular Tolerances

Shorter leg length (mm)	D1	D2	D3
≤ 30	30′	30′	20′
30 – 100	30′	20′	15′
100 – 200	30′	15′	10′

Radius Tolerances

Radius (mm)	D1	D2	D3
≤ 5	±0.30	±0.20	±0.15
5 – 10	±0.45	±0.35	±0.25
10 – 120	±0.70	±0.50	±0.40

Wall Thickness Tolerances

Shortest side of the unbroken surface (mm)	Tolerance (mm)
≤ 50	±0.25
50 – 100	±0.30
100 – 180	±0.40
180 – 315	±0.50
315 over	±0.60

Wall thickness tolerances do not depend on the accuracy class and apply to unmachined surfaces.

Surface Roughness

Class	Ra (µm)	CLA (µin)	Condition
N7	1.6	63	By agreement
N8	3.2	125	By agreement
N9	6.3	250	Standard delivery condition (shot blasted)

N9 applies unless otherwise stated on the drawing.

The tolerances for the ‘Investment Casting‘ process are defined by VDG P690, a reference sheet of the German foundry industry now published by the BDG (formerly VDG).

BRK Metal manufactures according to this standard, with Class D1 being the default standard. We can also cast to Class D3, the tightest class.

Class D1: Dimensions without a stated tolerance
Class D2: Dimensions toleranced on the drawing
Class D3: The tightest class, for individual dimensions by agreement with the foundry

Much of the production process at BRK Metal is automated. This leads to a reduction in process variation. Due to the presence of automation, the casting process is extremely consistent. This process allows BRK Metal to produce investment casting parts that are more precise than required by international standards.

General Dimensions: Investment casting parts often have complex and unique geometries. Therefore, the dimensions of each part are determined according to design requirements. Parts are typically expressed in dimensions in millimeters or inches.
Tolerances: The investment casting process can meet strict tolerance requirements. Tolerances can vary depending on the part’s dimensions, surface quality, and function. For example, surface coating requirements can affect tolerances. Tolerances commonly used in investment casting are ±0.1 mm or tighter. However, these tolerances can vary depending on specific applications and industries.
Inner and Outer Diameters: Inner and outer diameters are usually defined with specific tolerances in investment casting parts. For inner diameters, the size and tolerance of the inner diameter can be critical. For outer diameters, the size and tolerance of the outer diameter are important.
Wall Thickness: Wall thickness is another important feature to consider in investment casting. Tolerances can vary depending on the wall thickness and material properties.
Sharp Edges and Corners: Sharp edges and corners are frequently used in investment casting parts. The precision of these sharp corners and edges can affect tolerances.
Surface Quality: Surface quality is a significant factor in investment casting parts. Surface roughness and coating requirements can influence tolerances.

The dimensions and tolerances used in investment casting can vary greatly depending on specific applications and design requirements. During the design and production processes, the necessary precision and tolerances for specific parts should be carefully evaluated.

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Why BRK Metal?

Operating since 2002, BRK Metal exports 60% of its production and is an approved supplier to many well-known companies in Europe. Its customer-focused team produces at competitive cost without compromising on quality and delivers on time.

BRK Metal works under an ISO 9001:2015 quality management system, meets VDG P690 D3 tolerances and continues to invest in its technical infrastructure.