VDG P690: International standard casting tolerances

In the manufacturing world, precision is key, especially in casting.

Dimensional accuracy can make or break a component’s functionality, which is why tolerance standards are so important.

I waena o kēia mau, the VDG P690 standard is widely recognized for defining linear dimension tolerances in cast parts.

I kēia blog, we’ll dive into the details of VDG P690, its key aspects, how it compares to other tolerance standards, and why it is a cornerstone for quality control in casting.

1. Introduction to VDG P690

VDG P690 is a standard developed by the Association of German Foundry Experts (Verband Deutscher Giessereifachleute, VDG) that specifies linear dimensional tolerances for castings.

As casting processes can naturally lead to variations in part dimensions due to material behavior and production conditions, VDG P690 ensures that these deviations remain within acceptable limits.

This standard is used to maintain dimensional consistency, improve part reliability, and minimize potential issues during assembly.

Manufacturers across various industries rely on VDG P690 to guarantee the dimensional accuracy of cast parts, ensuring that they meet both functional and safety requirements.

Whether the application involves complex machinery, nā'āpana automotive, or large-scale industrial equipment, VDG P690 provides clear and detailed guidance.

2. Why Tolerances Are Important

Tolerances are critical in any manufacturing process because they define the allowable limits of deviation from the intended dimensions of a part.

In casting, where parts are often subject to shrinkage, ka hoʻonuiʻana, and other variables, dimensional tolerances help ensure that parts fit together correctly and perform their intended function.

Maintaining strict tolerances ensures that:

• Parts fit together correctly.
• Components function as intended.
• Quality and reliability are consistent across production batches.
• Scrap and rework are minimized, leading to cost savings.
• Customer satisfaction is maintained through reliable and high-quality products.

3. Dimensional Tolerances of VDG P690

The VDG P690 standard is structured around tolerance classes that correspond to different levels of dimensional precision.

Understanding the various aspects of this standard is crucial for both manufacturers and designers.

3.1 Linear tolerances

The dimensional tolerances achievable on investment castings are dependent on the following factors:

> casting material

> casting dimensions and shape

In production, the tolerance range of dispersion is affected by the varying characteristics of the materials.
For this reason, different tolerance series apply for different groups of casting materials:

• Material-group D: alloys based on iron-nickel, cobalt, and Cooper
  Accuracy grade: D1 to D3
• Material-group A: alloys based on aluminum and magnesium
  Accuracy grade: A1 to A3
• Material-group T: alloys based on titanium
  Accuracy grade: T1 to T3

Three accuracy grades are stated for each of the material groups D, A, and T.

• Accuracy grade 1 applies for all free-sized dimensions.
• Accuracy grade 2 applies for all dimensions to be toleranced.
• Accuracy grade 3 can only be met for certain dimensions and must be agreed upon with the casting manufacturer, as additional production processes and costly tooling adjustments are necessary.

Linear dimensional casting tolerances (DCT in mm) for dimensional casting tolerance grades (DCTG) material group D

	Nominal dimension Nā haʻona	D1		D2		D3
		DCT	DCTG	DCT	DCTG	DCT	DCTG
	a i 6	0,3	5	0,24	4	0,2	4
	luna 6 up i 10	0,36		0,28	5	0,22
	luna 10 up i 18	0,44	6	0,34		0,28
	luna 18 up i 30	0,52		0,4		0,34	5
	luna 30 up i 50	0,8	7	0,62	6	0,5
	luna 50 up i 80	0,9		0,74		0,6	6
	luna 80 up i 120	1,1		0,88		0,7
	luna 120 up i 180	1,6	8	1,3	7	1,0
	luna 180 up i 250	2,4	9	1,9	8	1,5	8
	luna 250 up i 315	2,6		2,2		1,6	7
	luna 315 up i 400	3,6	10	2,8	9
	luna 400 up i 500	4,0		3,2
	luna 500 up i 630	5,4	11	4,4	10
	luna 630 up i 800	6,2		5,0
	luna 800 up i 1000	7,2
	luna 1000 up i 1250

Linear dimensional casting tolerances (DCT in mm) for dimensional casting tolerance grades (DCTG) material group A

Nominal dimension Nā haʻona	A1		A2		A3
	DCT	DCTG	DCT	DCTG	DCT	DCTG
a i 6	0,3	5	0,24	4	0,2	4
luna 6 up i 10	0,36		0,28	5	0,22
luna 10 up i 18	0,44	6	0,34		0,28
luna 18 up i 30	0,52		0,4		0,34	5
luna 30 up i 50	0,8	7	0,62	6	0,5
luna 50 up i 80	0,9		0,74		0,6	6
luna 80 up i 120	1,1		0,88		0,7
luna 120 up i 180	1,6	8	1,3	7	1,0
luna 180 up i 250	1,9		1,5	8	1,2	7
luna 250 up i 315	2,6	9	2,2		1,6
luna 315 up i 400	2,8		2,4	9	1,7	8
luna 400 up i 500	3,2		2,6	8	1,9
luna 500 up i 630	4,4	10	3,4	9
luna 630 up i 800	5,0		4,0
luna 800 up i 1000	5,6		4,6	10
luna 1000 up i 1250	6,6

Linear dimensional casting tolerances (DCT in mm) for dimensional casting tolerance grades (DCTG) material group T

Nominal dimension Nā haʻona	T1		T2		T3
	DCT	DCTG	DCT	DCTG	DCT	DCTG
a i 6	0,5	6	0,4	6	0,4	6
luna 6 up i 10	0,6	7	0,4		0,4
luna 10 up i 18	0,7		0,5		0,44
luna 18 up i 30	0,8		0,7	7	0,52
luna 30 up i 50	1,0		0,8		0,62
luna 50 up i 80	1,5	8	1,2	8	0,9	7
luna 80 up i 120	1,7		1,4		1,1
luna 120 up i 180	2,0		1,6		1,3
luna 180 up i 250	2,4	9	1,9		1,5	8
luna 250 up i 315	3,2		2,6	9
luna 315 up i 400	3,6	10	2,8
luna 400 up i 500	4,0		3,2
luna 500 up i 630	5,4	11	4,4	10
luna 630 up i 800	6,2		5,0
luna 800 up i 1000	7,2
luna 1000 up i 1250

3.2 Angle tolerances for material groups D, A, and T

Nominal dimension Nā haʻona 1)	Accuracy3)
	1		2		3
	Allowed deviation na kuhikuhi
	Angular minute	mm per 100 mm	Angular minute	mm per 100 mm	Angular minute	mm per 100 mm
up i 30 mm	30 2)	0,87	30 2)	0,87	20 2)	0,58
luna 30 up i 100 mm	30 2)	0,87	20 2)	0,58	15 2)	0,44
luna 100 up i 200 mm	30 2)	0,87	15 2)	0,44	10 2)	0,29
luna 200 mm	30 2)	0,58	15 2)	0,44	10 2)	0,29

Table 2: Angle tolerances

Tolerances deviating from Table 2 must be agreed on between supplier and user and entered in the drawing following DIN ISO 1101.

3.3 Radius of curvature

The tolerances stated apply to the material groups D, A, and T

Nominal dimension Nā haʻona	Accuracy1)
	1	2	3
	The radius of curvature [mm]
up i 5 mm	± 0,30	± 0,20	± 0,15
luna 5 up i 10 mm	± 0,45	± 0,35	± 0,25
luna 10 up i 120 mm	± 0,70	± 0,50	± 0,40
luna 120 mm	linear (cf. table 1)

Table 3: Radius of curvature for material groups D, A and T

Radii of curvature deviating from Table 3 must be agreed on with the investment casting foundry.

3.4 Surface quality

For cast surfaces, Ra (CLA) shall be applied following table

Puni kūlā	Waiwai group D		Waiwai group A		Waiwai group T
	CLA [µinch]	Ra [}m]	CLA [µinch]	Ra [}m]	CLA [µinch]	Ra [}m]
N 7	63	1,6
N 8	125	3,2	125	3,2
N 9	250	6,3	250	6,3	250	6,3

Zone N7, N8, and special surface treatment must be agreed separately and entered in the drawing following DIN ISO 1302.
Unless otherwise agreed, N9 in the shot-blasted state is the standard delivery condition.

4. Factors Affecting Dimensional Tolerances

Several factors influence the dimensional tolerances of cast parts, making it important to understand these variables when applying VDG P690 standards:

• Waiwai waiwai: Different materials react differently during the casting process.
  ʻo kahi laʻana, aluminum and steel may experience different rates of shrinkage or warping as they cool, which can affect the final dimensions.
• Ke Kūleʻa Kūlana: The choice of casting method—whether sand casting, make buring, or investment casting—can also impact the achievable tolerances.
  Make buring, ʻo kahi laʻana, generally allows for tighter tolerances than sand casting due to the more controlled nature of the process.
• Part Complexity: More intricate designs or parts with complex geometries are more prone to dimensional deviations.
  Parts with thin walls, small features, or intricate shapes may require more precise control over tolerances to ensure accuracy.

5. How VDG P690 Improves Quality Control

The VDG P690 standard plays a critical role in enhancing quality control in casting operations. Clearly defining tolerance limits.

Helps manufacturers maintain consistent product quality across batches and production runs. This leads to several key benefits:

• Reduced Waste: By ensuring that parts meet tolerance requirements, manufacturers minimize the number of rejected or scrapped parts, reducing waste and costs.
• Improved Assembly: Properly toleranced parts fit together more easily, reducing the likelihood of assembly errors and ensuring that products work as intended.
• Enhanced Customer Satisfaction: Consistency in casting dimensions leads to fewer customer complaints and warranty claims, improving overall satisfaction and building long-term trust with clients.

6. VDG P690 vs. Other Tolerance Standards

VDG P690 is one of several tolerance standards used in the casting industry. How does it compare to other standards, such as ISO 8062 or ASTM A956?

• VDG P690: This standard is particularly known for its detailed classification of tolerances across different part sizes and tolerance classes,
  offering more granular control over precision than some other standards.
• Iso 8062: Iso 8062 is a more globally recognized standard for casting tolerances and covers a broad range of materials and casting processes.
  Akā naʻe,, it is often viewed as less specific in certain cases compared to VDG P690.
• ASTM A956: Primarily used in the United States, ASTM standards provide guidelines for specific casting materials.
  ASTM A956, ʻo kahi laʻana, focuses on the hardness of cast parts rather than linear dimensional tolerances, making it complementary to standards like VDG P690.

7. Hopena

VDG P690 stands as a vital tool for ensuring the precision and reliability of cast components.

Its comprehensive classification of tolerance classes and flexibility in addressing different part sizes and complexities make it an indispensable standard for manufacturers.

By adhering to the VDG P690 standard, manufacturers can achieve better product performance, reduce waste, and enhance customer satisfaction.

If you’re involved in casting or using cast parts in your products, understanding and applying VDG P690 is essential for maintaining quality and meeting the demands of modern manufacturing.

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