Construction and How to Use It
What is a Sine Bar?
A sine bar is a precision tool used in metrology for measuring angles with high accuracy. It consists of a hardened, precision ground body with two identical cylinders fixed at the ends. The distance between the centers of the cylinders is precisely controlled.
Construction of a Sine Bar
The construction of a sine bar involves the following components:
- Body: A flat, rectangular block made of high-quality steel or cast iron.
- Cylinders: Two precision-ground cylinders mounted on the body at a fixed distance apart.
- Surface Plates: Used as a reference plane when using the instrument.
How to Use a Sine Bar
Sine bars are widely employed in industries demanding precise angle measurements. In machining, they are used to set the angles of milling heads, grinders, and other tools. Metalworking utilizes them to measure the angles of saw blades, drill bits, and other cutting tools. Furthermore, sine bars are essential in manufacturing for the accurate alignment of parts and machines. Some of the applications of a sine bar are:
- Setting and Checking the Angle of Cutting Tools
- Aligning Workpieces on Machine Tables
- Measuring the Angle of Surfaces during Inspection
- Measuring Angles in Research and Development
To use a sine bar for measuring or setting an angle, follow these steps:
- Place the Sine Bar on a Surface Plate: Ensure the surface plate is clean and free of debris.
- Set the Desired Angle: Calculate the height of the gauge blocks needed based on the sine of the desired angle. The formula is:
Height = Distance Between Cylinders × sin(Desired Angle) - Position Gauge Blocks: Place the calculated height of gauge blocks under one cylinder of the sine bar.
- Verify the Setup: Use a dial indicator or spirit level to ensure the top surface is parallel to the desired angle.
Applications of a Sine Bar
Sine bars are widely used in industries for various applications, including:
- Setting up workpieces at precise angles during machining.
- Inspecting machined parts for angular accuracy.
- Calibrating other measuring instruments.
Conclusion
The sine bar is an essential tool for achieving accurate angular measurements in manufacturing and quality control processes. Its simplicity and reliability make it indispensable in many industrial settings.
Manufacturing and calibration standards
The manufacturing and calibration of sine bars are governed by several national and international standards, as indicated by the provided web_search content:
Manufacturing Standards
- BS 3064:1978 (2012):
- A British Standard specifying requirements for metric sine bars and sine tables (excluding compound tables) .
- Defines tolerances and design criteria for commercial and laboratory-grade sine bars .
- IS 5359:1987:
- An Indian Standard referenced for the design and manufacturing of sine bars, ensuring precision and hardness (e.g., 55–60 HRC for hardened steel models) .
- IS 16491 (Part 1):2016:
- Aligns with ISO 13385-1:2011, covering dimensional measuring equipment requirements, including sine bars .
Calibration Standards
- NIST Traceable Calibration:
- Sine bars are calibrated using master standards like coordinate measuring machines (CMMs) to ensure traceability to the National Institute of Standards and Technology (NIST) .
- ISO/IEC 17025 Compliance:
- Calibration laboratories often adhere to ISO/IEC 17025 for quality management, ensuring accurate and consistent results .
- IS 12754-2:1989:
- Part of Indian Standards for process measurement control, relevant to calibration practices ..
These standards ensure sine bars meet precision, durability, and interoperability requirements for industrial and metrological applications.
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