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.

Näiden joukossa, the VDG P690 standard is widely recognized for defining linear dimension tolerances in cast parts.

Tässä blogissa, 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, autojen komponentit, 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.

Valettaessa, where parts are often subject to shrinkage, lämmön laajennus, 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:

• Materiaaliryhmä D: Seokset, jotka perustuvat Iron-Nickeliin, koboltti, ja Cooper
  Tarkkuusluokka: D1 - D3
• Material-group A: alloys based on aluminum and magnesium
  Tarkkuusluokka: A1 to A3
• Material-group T: alloys based on titanium
  Tarkkuusluokka: T1 to T3

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

• Tarkkuusluokka 1 applies for all free-sized dimensions.
• Tarkkuusluokka 2 applies for all dimensions to be toleranced.
• Tarkkuusluokka 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.

Lineaarinen ulottuvuusvalutoleranssit (Dct mm) ulottuvuuden toleranssiarvosat (Dctg) materiaaliryhmä D

	Nominal dimension etäisyys	D1		D2		D3
		Dct	Dctg	Dct	Dctg	Dct	Dctg
	jopa 6	0,3	5	0,24	4	0,2	4
	yli 6 up -lla 10	0,36		0,28	5	0,22
	yli 10 up -lla 18	0,44	6	0,34		0,28
	yli 18 up -lla 30	0,52		0,4		0,34	5
	yli 30 up -lla 50	0,8	7	0,62	6	0,5
	yli 50 up -lla 80	0,9		0,74		0,6	6
	yli 80 up -lla 120	1,1		0,88		0,7
	yli 120 up -lla 180	1,6	8	1,3	7	1,0
	yli 180 up -lla 250	2,4	9	1,9	8	1,5	8
	yli 250 up -lla 315	2,6		2,2		1,6	7
	yli 315 up -lla 400	3,6	10	2,8	9
	yli 400 up -lla 500	4,0		3,2
	yli 500 up -lla 630	5,4	11	4,4	10
	yli 630 up -lla 800	6,2		5,0
	yli 800 up -lla 1000	7,2
	yli 1000 up -lla 1250

Lineaarinen ulottuvuusvalutoleranssit (Dct mm) ulottuvuuden toleranssiarvosat (Dctg) material group A

Nominal dimension etäisyys	A1		A2		A3
	Dct	Dctg	Dct	Dctg	Dct	Dctg
jopa 6	0,3	5	0,24	4	0,2	4
yli 6 up -lla 10	0,36		0,28	5	0,22
yli 10 up -lla 18	0,44	6	0,34		0,28
yli 18 up -lla 30	0,52		0,4		0,34	5
yli 30 up -lla 50	0,8	7	0,62	6	0,5
yli 50 up -lla 80	0,9		0,74		0,6	6
yli 80 up -lla 120	1,1		0,88		0,7
yli 120 up -lla 180	1,6	8	1,3	7	1,0
yli 180 up -lla 250	1,9		1,5	8	1,2	7
yli 250 up -lla 315	2,6	9	2,2		1,6
yli 315 up -lla 400	2,8		2,4	9	1,7	8
yli 400 up -lla 500	3,2		2,6	8	1,9
yli 500 up -lla 630	4,4	10	3,4	9
yli 630 up -lla 800	5,0		4,0
yli 800 up -lla 1000	5,6		4,6	10
yli 1000 up -lla 1250	6,6

Lineaarinen ulottuvuusvalutoleranssit (Dct mm) ulottuvuuden toleranssiarvosat (Dctg) material group T

Nominal dimension etäisyys	T1		T2		T3
	Dct	Dctg	Dct	Dctg	Dct	Dctg
jopa 6	0,5	6	0,4	6	0,4	6
yli 6 up -lla 10	0,6	7	0,4		0,4
yli 10 up -lla 18	0,7		0,5		0,44
yli 18 up -lla 30	0,8		0,7	7	0,52
yli 30 up -lla 50	1,0		0,8		0,62
yli 50 up -lla 80	1,5	8	1,2	8	0,9	7
yli 80 up -lla 120	1,7		1,4		1,1
yli 120 up -lla 180	2,0		1,6		1,3
yli 180 up -lla 250	2,4	9	1,9		1,5	8
yli 250 up -lla 315	3,2		2,6	9
yli 315 up -lla 400	3,6	10	2,8
yli 400 up -lla 500	4,0		3,2
yli 500 up -lla 630	5,4	11	4,4	10
yli 630 up -lla 800	6,2		5,0
yli 800 up -lla 1000	7,2
yli 1000 up -lla 1250

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

Nominal dimension etäisyys 1)	Tarkkuus3)
	1		2		3
	Allowed deviation - suunta
	Angular minute	mm - 100 mm	Angular minute	mm - 100 mm	Angular minute	mm - 100 mm
up -lla 30 mm	30 2)	0,87	30 2)	0,87	20 2)	0,58
yli 30 up -lla 100 mm	30 2)	0,87	20 2)	0,58	15 2)	0,44
yli 100 up -lla 200 mm	30 2)	0,87	15 2)	0,44	10 2)	0,29
yli 200 mm	30 2)	0,58	15 2)	0,44	10 2)	0,29

Taulukko 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, Eräs, and T

Nominal dimension etäisyys	Tarkkuus1)
	1	2	3
	The radius of curvature [mm]
up -lla 5 mm	± 0,30	± 0,20	± 0,15
yli 5 up -lla 10 mm	± 0,45	± 0,35	± 0,25
yli 10 up -lla 120 mm	± 0,70	± 0,50	± 0,40
yli 120 mm	lineaarinen (cf. table 1)

Taulukko 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, Rata (CLA) shall be applied following table

Pinta standardit	Materiaali group D -d		Materiaali group Eräs		Materiaali group T
	CLA [µinch]	Reräs [µm]	CLA [µinch]	Reräs [µm]	CLA [µinch]	Reräs [µm]
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:

• Materiaaliominaisuudet: Different materials react differently during the casting process.
  Esimerkiksi, aluminum and steel may experience different rates of shrinkage or warping as they cool, which can affect the final dimensions.
• Casting -menetelmä: The choice of casting method—whether sand casting, kuolla casting, or investment casting—can also impact the achievable tolerances.
  Kuolla casting, esimerkiksi, 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:

• Vähentynyt jäte: 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, kuten 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.
  Kuitenkin, 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, esimerkiksi, focuses on the hardness of cast parts rather than linear dimensional tolerances, making it complementary to standards like VDG P690.

7. Johtopäätös

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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