DOCSLIB.ORG

Npl Notes on Screw Gauges

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text

Load more

TABLE OF CONTENTS NPL NOTES ON SCREW GAUGES ...........................................................................................................................1 FOREWORD ..................................................................................................................................................1 PART I: INTRODUCTION...........................................................................................................................................2 1 SCOPE ..............................................................................................................................................2 2 DEFINITIONS..................................................................................................................................3 2.1 General definitions for screws ............................................................................................3 2.2 Definitions for parallel screw threads .................................................................................4 2.3 Definitions relating to taper screw threads .........................................................................5 3 ELEMENTS OF A SCREW THREAD AND THEIR ERRORS .....................................................5 3.1 Pitch diameter .....................................................................................................................5 3.2 Pitch....................................................................................................................................6 3.3 Error in pitch in relation to pitch diameter..........................................................................7 3.4 Errors in flank angles in relation to pitch diameter.............................................................8 3.5 Radii at crest and root .........................................................................................................9 3.6 Summary.............................................................................................................................9 4 GAUGING PARALLEL SCREW THREADS...............................................................................10 4.1 Gauges for external threads ..............................................................................................10 4.2 Gauges for internal threads ...............................................................................................10 4.3 Length of gauge ................................................................................................................10 4.4 Thread form of gauge .......................................................................................................10 5 PREPARATORY FEATURES OF GAUGES................................................................................11 5.1 Gauge blanks ....................................................................................................................11 5.2 Hardness and stabilization ................................................................................................11 5.3 Centre of plugs; end faces of rings ...................................................................................11 5.4 End threading....................................................................................................................12 PART II: PARALLEL SCREW THREADS ..................................................................................................13 6 CONDITIONS OF MEASUREMENT...........................................................................................13 6.1 Temperature......................................................................................................................13 6.2 Units..................................................................................................................................13 7 MECHANICAL MEASUREMENTS OF PARALLEL SCREW PLUG GAUGES ......................13 7.1 Major diameter..................................................................................................................13 7.2 Pitch diameter ...................................................................................................................14 7.3 Minor diameter .................................................................................................................18 7.4 Pitch..................................................................................................................................19 7.4.1 "Drunkenness" ..................................................................................................................21 7.5 Thread form and flank angles ...........................................................................................22 8 FORMULAE AND CORRECTIONS FOR USE IN THE MEASUREMENT OF THE PITCH DIAMETER OF PARALLEL SCREW PLUG GAUGES BY MEANS OF SMALL CYLINDERS ..................................................................................................................................23 8.1 Formula for calculating pitch diameter E of thread with symmetrical flank angles .........23 8.2 Determination of rake correction, c ..................................................................................25 8.3 Correction e for the elastic compression of cylinders.......................................................27 8.4 Consideration of rake and compression corrections .........................................................28 8.5 Measurement of pitch diameter using cylinders other than best size................................29 8.6 Measurement of thread angle using cylinders of different sizes.......................................31 9 MECHANICAL MEASUREMENTS OF PARALLEL SCREW RING GAUGES.......................32 9.1 Minor diameter .................................................................................................................32 9.2 Pitch diameter ...................................................................................................................33 9.2.1 Displacement method .......................................................................................................33 9.2.2 Radial method...................................................................................................................35 9.2.3 Horizontal diametral comparators.....................................................................................38 9.3 Pitch..................................................................................................................................39 9.4 Thread form and angle......................................................................................................39 10 INSPECTION OF PARALLEL SCREW RING GAUGES WITH CHECK PLUGS ....................40 11 TESTING OF SCREW CALLIPER GAUGES ..............................................................................41 12 OPTICAL PROJECTION APPARATUS.......................................................................................42 12.1 Horizontal projector..........................................................................................................43 12.2 Examination of thread form..............................................................................................44 12.3 Modern projectors.............................................................................................................45 12.4 Measurement of flank angles............................................................................................47 12.4.1 Improved protractor and throwover method of flank angle measurement........................48 PART III: TAPER SCREW THREADS..........................................................................................................50 13 SCOPE ............................................................................................................................................50 14 DEFINITIONS FOR TAPER SCREW THREADS, SEE FIG. 28 .................................................50 15 GAUGING TAPER SCREW THREADS ON COMPONENTS....................................................51 16 MEASUREMENT OF TAPER SCREW PLUG GAUGES............................................................52 16.1 Elements to be measured ..................................................................................................52 16.2 Measurement of pitch, major, and minor diameters .........................................................52 16.2.1 "Spotting off" to locate the specified plane.......................................................................52 16.2.2 Measurement of pitch diameter in a floating micrometer machine...................................53 16.2.3 NPL/Matrix radial measuring machine.............................................................................55 16.2.4 NPL double sine bar machine...........................................................................................55 16.3 Measurement of taper .......................................................................................................58 16.3.1 Floating micrometer machine ...........................................................................................58 16.3.2 Double sine bar machine...................................................................................................58 16.3.3 Minor diameter: major diameter ......................................................................................58 16.4 Measurement of pitch .......................................................................................................58
Recommended publications
  • Check Points for Measuring Instruments

    Check Points for Measuring Instruments

    Catalog No. E12024 Check Points for Measuring Instruments Introduction Measurement… the word can mean many things. In the case of length measurement there are many kinds of measuring instrument and corresponding measuring methods. For efficient and accurate measurement, the proper usage of measuring tools and instruments is vital. Additionally, to ensure the long working life of those instruments, care in use and regular maintenance is important. We have put together this booklet to help anyone get the best use from a Mitutoyo measuring instrument for many years, and sincerely hope it will help you. CONVENTIONS USED IN THIS BOOKLET The following symbols are used in this booklet to help the user obtain reliable measurement data through correct instrument operation. correct incorrect CONTENTS Products Used for Maintenance of Measuring Instruments 1 Micrometers Digimatic Outside Micrometers (Coolant Proof Micrometers) 2 Outside Micrometers 3 Holtest Digimatic Holtest (Three-point Bore Micrometers) 4 Holtest (Two-point/Three-point Bore Micrometers) 5 Bore Gages Bore Gages 6 Bore Gages (Small Holes) 7 Calipers ABSOLUTE Coolant Proof Calipers 8 ABSOLUTE Digimatic Calipers 9 Dial Calipers 10 Vernier Calipers 11 ABSOLUTE Inside Calipers 12 Offset Centerline Calipers 13 Height Gages Digimatic Height Gages 14 ABSOLUTE Digimatic Height Gages 15 Vernier Height Gages 16 Dial Height Gages 17 Indicators Digimatic Indicators 18 Dial Indicators 19 Dial Test Indicators (Lever-operated Dial Indicators) 20 Thickness Gages 21 Gauge Blocks Rectangular Gauge Blocks 22 Products Used for Maintenance of Measuring Instruments Mitutoyo products Micrometer oil Maintenance kit for gauge blocks Lubrication and rust-prevention oil Maintenance kit for gauge Order No.207000 blocks includes all the necessary maintenance tools for removing burrs and contamination, and for applying anti-corrosion treatment after use, etc.
  • Micro-Ruler MR-1 a NPL (NIST Counterpart in the U.K.)Traceable Certified Reference Material

    Micro-Ruler MR-1 a NPL (NIST Counterpart in the U.K.)Traceable Certified Reference Material

    Micro-Ruler MR-1 A NPL (NIST counterpart in the U.K.)Traceable Certified Reference Material . ATraceable “Micro-Ruler”. Markings are all on one side. Mirror image markings are provided so right reading numbers are always seen. The minimum increment is 0.01mm. The circles (diameter) and square boxes (side length) are 0.02, 0.05, 0.10, 0.50, 1.00, 2.00 and 5.00mm. 150mm OVERALL LENGTH 150mm uncertainty: ±0.0025mm, 0-10mm: ±0.0005mm) 0.01mm INCREMENTS, SQUARES & CIRCLES UP TO 5mm TED PELLA, INC. Microscopy Products for Science and Industry P. O. Box 492477 Redding, CA 96049-2477 Phone: 530-243-2200 or 800-237-3526 (USA) • FAX: 530-243-3761 [email protected] www.tedpella.com DOES THE WORLD NEED A TRACEABLE RULER? The MR-1 is labeled in mm. Its overall scale extends According to ISO, traceable measurements shall be over 150mm with 0.01mm increments. The ruler is designed to be viewed from either side as the markings made when products require the dimensions to be are both right reading and mirror images. This allows known to a specified uncertainty. These measurements the ruler marking to be placed in direct contact with the shall be made with a traceable ruler or micrometer. For sample, avoiding parallax errors. Independent of the magnification to be traceable the image and object size ruler orientation, the scale can be read correctly. There is must be measured with calibration standards that have a common scale with the finest (0.01mm) markings to traceable dimensions. read. We measure and certify pitch (the distance between repeating parallel lines using center-to-center or edge-to- edge spacing.
  • AMC Precision, Inc

    AMC Precision, Inc

    AMC Precision, Inc 430 Robinson Street North Tonawanda, NY 14120 Onsite and Webcast Auction Tuesday, February 10th, 10:00 AM EST Blackbird Asset Services, LLC CATALOG 5586 Main Street Suite 204 Williamsville, NY 14221 716-632-1000 www.blackbirdauctions.com Auction Bidder Agreement Bidder and Auctioneer agree that the Terms and Conditions listed below shall govern this Auction sale: 1. All persons seeking to register to bid acknowledges acceptance of these terms of sale, and guarantees prompt payment of all purchases by ACH, wire transfer, credit card or company check with bank letter of guarantee. No items will be removed prior to full payment, with all funds having cleared our accounts. 2. The "Bidder" becomes a "Buyer" upon the Auctioneers acceptance of their bid on one or more items in the Auction sale. 3. FULL PAYENT must be made immediately for your purchase at the Auction. This payment should be made in the form of cash, credit card (up to $5,000), company check with bank letter, cashiers check, wire transfer or ACH (see wire instructions on invoice). 4. Items left unpaid for more than 48 hours will be resold at the risk and expense of the Buyer. In the event that a Buyer fails to pay the entire purchase price (in addition to the Buyer's premium and any applicable tax) within 48 hours or otherwise fails to comply with these Terms and Conditions, Auctioneer and the Seller may retain any deposit paid as liquidated damages without notice. Auctioneer and the Seller reserve the right to resell such items without notice, and the defaulting Buyer shall be liable to Auctioneer and Seller for any resulting deficiency, including costs incurred in storing and reselling such items.
  • Height Gage an Inspection Certificate Is Supplied As Standard

    Height Gage an Inspection Certificate Is Supplied As Standard

    Height Gage An inspection certificate is supplied as standard. A standard measuring tool of industry Refer to page X for details. Linear Height SERIES 518 — High Performance 2D Measurement System Technical Data Measuring range: 0 - 977mm • Excellent accuracy of (1.1+0.6L/600)μm with • Pneumatic full/semi-floating system allows Slider stroke: 600mm Resolution: 0.0001 / 0.001 / 0.01 / 0.1mm or 0.1μm/0.4μm resolution/repeatability. adjustment of air-cushion height. (switchable) .000001” / .00001” / .0001” / .001” • High-accuracy Height Gage incorporating a • Basic statistical functions are provided and, Accuracy at 20°C*1: (1.1+0.6L/600)μm wide range of measurement functions. additionally, RS-232C data output provides L = Measuring length (mm) Repeatability (2σ)*1: Plane: 0.4μm, Bore: 0.9μm • To achieve best-in-class accuracy, a high- the option of evaluating measurement data Perpendicularity*2: 5μm (after compensation) accuracy reflective-type linear encoder and externally with SPC software on a PC. Straightness*2: 4μm (mechanical straightness) Drive method: Manual / motor (5 - 40mm/s, 7 steps) high-accuracy guide are used. • For precision Black Granite Surface Plates, Measuring force: 1N • Measurement can be implemented by icon- refer to page E-51. Balancing method: Counter balance based commands that also support easy one- • Backup/Restore of data and measurement Floating method: Full / semi-floating with built-in air compressor key operation. part programs can be implemented using Display: 5.7-inch color TFT LCD Perpendicularity (frontal) of 5μm and USB storage devices (FAT16/32 format Language for display: Japanese, English, German, French, Italian, Spanish, Dutch, Portuguese, straightness of 4μm are guaranteed.
  • Notes on Using the Height Gage

    Notes on Using the Height Gage

    3. Lifting of the base from the reference surface Notes on using the height gage When setting the scriber height from a gauge block stack, or from a workpiece feature, the base may lift from the surface plate if excessive downwards force is 1. Keep the column, which guides the slider, clean. If dust or dirt accumulates used on the slider, and this results in measurement error. For accurate setting, on it, sliding becomes difficult, leading to errors in setting and measuring. move the slider slowly downwards while moving the scriber tip to and fro over the gauge block surface (or feature). The correct setting is when the scriber 2. When scribing, securely lock the slider in position using the clamping PG is just felt to lightly touch as it moves over the edge of the surface. It is also arrangements provided. It is advisable to confirm the setting after clamping 25 necessary to make sure that the surface plate and height gage base reference because the act of clamping on some height gages can alter the setting surface are free of dust or burrs before use. slightly. If this is so, allowance must be made when setting to allow for this effect. 3. Parallelism between the scriber measuring face and the base reference surface should be 0.01 mm or better. Remove any dust or burrs on the mounting surface when installing the scriber or lever-type dial indicator before measurement. Keep the scriber and other parts securely fixed in place during measurement. 4. If the main scale of the height gage can be moved, move it as required to set the zero point, and securely tighten the fixing nuts.
  • Surfaceview Manual

    Surfaceview Manual

    Table of Contents Overview ..................................................................................................................................3 Conventions used in this manual. .............................................................................................4 SurfaceView Union Jack ................................................................................................................................................5 Getting Started.......................................................................................................................5 Description of User Interface....................................................................................................8 Job Set Up ............................................................................................................................9 ELCOMAT Set Up (Ignore this if you use an electronic level or a visual autocollimator) ..............11 Administrator Functions.....................................................................................................13 Plate Measurement................................................................................................................18 Base Length ....................................................................................................................19 Diagonal Base Length .......................................................................................................22 Automated Data Collection.................................................................................................25
  • Verification Regulation of Steel Ruler

    Verification Regulation of Steel Ruler

    ITTC – Recommended 7.6-02-04 Procedures and guidelines Page 1 of 15 Effective Date Revision Calibration of Micrometers 2002 00 ITTC Quality System Manual Sample Work Instructions Work Instructions Calibration of Micrometers 7.6 Control of Inspection, Measuring and Test Equipment 7.6-02 Sample Work Instructions 7.6-02-04 Calibration of Micrometers Updated / Edited by Approved Quality Systems Group of the 28th ITTC 23rd ITTC 2002 Date: 07/2017 Date: 09/2002 ITTC – Recommended 7.6-02-04 Procedures and guidelines Page 2 of 15 Effective Date Revision Calibration of Micrometers 2002 00 Table of Contents 1. PURPOSE .............................................. 4 4.6 MEASURING FORCE ......................... 9 4.6.1 Requirements: ............................... 9 2. INTRODUCTION ................................. 4 4.6.2 Calibration Method: ..................... 9 3. SUBJECT AND CONDITION OF 4.7 WIDTH AND WIDTH DIFFERENCE CALIBRATION .................................... 4 OF LINES .............................................. 9 3.1 SUBJECT AND MAIN TOOLS OF 4.7.1 Requirements ................................ 9 CALIBRATION .................................... 4 4.7.2 Calibration Method ...................... 9 3.2 CALIBRATION CONDITIONS .......... 5 4.8 RELATIVE POSITION OF INDICATOR NEEDLE AND DIAL.. 10 4. TECHNICAL REQUIREMENTS AND CALIBRATION METHOD ................. 7 4.8.1 Requirements .............................. 10 4.8.2 Calibration Method: ................... 10 4.1 EXTERIOR ............................................ 7 4.9 DISTANCE
  • Vernier Caliper and Micrometer Computer Models Using Easy Java Simulation and Its Pedagogical Design Features—Ideas for Augmenting Learning with Real Instruments

    Vernier Caliper and Micrometer Computer Models Using Easy Java Simulation and Its Pedagogical Design Features—Ideas for Augmenting Learning with Real Instruments

    Wee, Loo Kang, & Ning, Hwee Tiang. (2014). Vernier caliper and micrometer computer models using Easy Java Simulation and its pedagogical design features—ideas for augmenting learning with real instruments. Physics Education, 49(5), 493. Vernier caliper and micrometer computer models using Easy Java Simulation and its pedagogical design feature-ideas to augment learning with real instruments Loo Kang WEE1, Hwee Tiang NING2 1Ministry of Education, Educational Technology Division, Singapore 2 Ministry of Education, National Junior College, Singapore [email protected], [email protected] Abstract: This article presents the customization of EJS models, used together with actual laboratory instruments, to create an active experiential learning of measurements. The laboratory instruments are the vernier caliper and the micrometer. Three computer model design ideas that complement real equipment are discussed in this article. They are 1) the simple view and associated learning to pen and paper question and the real world, 2) hints, answers, different options of scales and inclusion of zero error and 3) assessment for learning feedback. The initial positive feedback from Singaporean students and educators points to the possibility of these tools being successfully shared and implemented in learning communities, and validated. Educators are encouraged to change the source codes of these computer models to suit their own purposes, licensed creative commons attribution for the benefit of all humankind. Video abstract: http://youtu.be/jHoA5M-_1R4 2015 Resources: http://iwant2study.org/ospsg/index.php/interactive-resources/physics/01-measurements/5-vernier-caliper http://iwant2study.org/ospsg/index.php/interactive-resources/physics/01-measurements/6-micrometer Keyword: easy java simulation, active learning, education, teacher professional development, e–learning, applet, design, open source physics PACS: 06.30.Gv 06.30.Bp 1.50.H- 01.50.Lc 07.05.Tp I.
  • MICHIGAN STATE COLLEGE Paul W

    MICHIGAN STATE COLLEGE Paul W

    A STUDY OF RECENT DEVELOPMENTS AND INVENTIONS IN ENGINEERING INSTRUMENTS Thai: for III. Dean. of I. S. MICHIGAN STATE COLLEGE Paul W. Hoynigor I948 This]: _ C./ SUPP! '3' Nagy NIH: LJWIHL WA KOF BOOK A STUDY OF RECENT DEVELOPMENTS AND INVENTIONS IN ENGINEERING’INSIRUMENTS A Thesis Submitted to The Faculty of MICHIGAN‘STATE COLLEGE OF AGRICULTURE AND.APPLIED SCIENCE by Paul W. Heyniger Candidate for the Degree of Batchelor of Science June 1948 \. HE-UI: PREFACE This Thesis is submitted to the faculty of Michigan State College as one of the requirements for a B. S. De- gree in Civil Engineering.' At this time,I Iish to express my appreciation to c. M. Cade, Professor of Civil Engineering at Michigan State Collegeafor his assistance throughout the course and to the manufacturers,vhose products are represented, for their help by freely giving of the data used in this paper. In preparing the laterial used in this thesis, it was the authors at: to point out new develop-ants on existing instruments and recent inventions or engineer- ing equipment used principally by the Civil Engineer. 20 6052 TAEEE OF CONTENTS Chapter One Page Introduction B. Drafting Equipment ----------------------- 13 Chapter Two Telescopic Inprovenents A. Glass Reticles .......................... -32 B. Coated Lenses .......................... --J.B Chapter three The Tilting Level- ............................ -33 Chapter rear The First One-Second.Anerican Optical 28 “00d011 ‘6- -------------------------- e- --------- Chapter rive Chapter Six The Latest Type Altineter ----- - ................ 5.5 TABLE OF CONTENTS , Chapter Seven Page The Most Recent Drafting Machine ........... -39.--- Chapter Eight Chapter Nine SmOnnB By Radar ....... - ------------------ In”.-- Chapter Ten Conclusion ------------ - ----- -.
  • MODULE 5 – Measuring Tools

    MODULE 5 – Measuring Tools

    INTRODUCTION TO MACHINING 2. MEASURING TOOLS AND PROCESSES: In this chapter we will only look at those instruments which would typically be used during and at the end of a fabrication process. Such instruments would be capable of measuring up to 4 decimal places in the inch system and up to 3 decimal places in the metric system. Higher precision is normally not required in shop settings. The discrimination of a measuring instrument is the number of “segments” to which it divides the basic unit of length it is using for measurement. As a rule of thumb: the discrimination of the instrument should be ~10 times finer than the dimension specified. For example if a dimension of 25.5 [mm] is specified, an instrument that is capable of measuring to 0.01 or 0.02 [mm] should be used; if the specified dimension is 25.50 [mm], then the instrument’s discrimination should be 0.001 or 0.002 [mm]. The tools discussed here can be divided into 2 categories: direct measuring tools and indirect measuring or comparator tools. 50 INTRODUCTION TO MACHINING 2.1 Terminology: Accuracy: can have two meanings: it may describe the conformance of a specific dimension with the intended value (e.g.: an end-mill has a specific diameter stamped on its shank; if that value is confirmed by using the appropriate measuring device, then the end-mill diameter is said to be accurate). Accuracy may also refer to the act of measuring: if the machinist uses a steel rule to verify the diameter of the end-mill, then the act of measuring is not accurate.
  • Moore & Wright 2016/17- Complete Catalogue

    Moore & Wright 2016/17- Complete Catalogue

    MW-2016E MW-2016E MOORE & WRIGHT Moore & Wright - Europe and North Africa Moore & Wright - Rest of the World Bowers Group Bowers Eclipse Equipment (Shanghai) Co., Ltd. Unit 3, Albany Court, 8th Building, No. 178 Chengjian Rd Albany Park, Camberley, Minhang District, Shanghai 201108 Surrey GU16 7QR, UK P.R.China Telephone: +44 (0)1276 469 866 Telephone: +86 21 6434 8600 Fax: +44 (0)1276 401 498 Fax: +86 21 6434 6488 Email: [email protected] Email: [email protected] Website: www.moore-and-wright.com Website : www.moore-and-wright.com PRODUCT CATALOGUE 16/17 Partners in Precision PRODUCT CATALOGUE 16/17 INNOVATIVE NEW PRODUCTS IN EVERY SECTION OF THIS ALL-INCLUSIVE, EASY TO USE REFERENCE MWEX2016-17_FC-BC.indd 1 19/11/2015 11:58 MOORE & WRIGHT A Brief History... Founded in 1906 by innovative young engineer, Frank Moore, Moore & Wright has been designing, manufacturing and supplying precision measuring equipment to global industry for over 100 years. With roots fixed firmly in Sheffield, England, the company began by manufacturing a range of calipers, screwdrivers, punches and other engineer’s tools. Following investment from Mrs Wright, a shrewd Sheffield businesswoman, Frank was able to expand the business and further develop his innovative designs. By the mid-nineteen twenties, thanks to the company’s enviable reputation, Moore & Wright was approached by the UK Government to consider manufacturing a range of quality micrometers. It was in this field that Moore & Wright’s status as UK agent for the Swiss Avia range of products and subsequent acquisition of the Avia brand and manufacturing rights, proved invaluable.
  • Quick Guide to Precision Measuring Instruments

    Quick Guide to Precision Measuring Instruments

    E4329 Quick Guide to Precision Measuring Instruments Coordinate Measuring Machines Vision Measuring Systems Form Measurement Optical Measuring Sensor Systems Test Equipment and Seismometers Digital Scale and DRO Systems Small Tool Instruments and Data Management Quick Guide to Precision Measuring Instruments Quick Guide to Precision Measuring Instruments 2 CONTENTS Meaning of Symbols 4 Conformance to CE Marking 5 Micrometers 6 Micrometer Heads 10 Internal Micrometers 14 Calipers 16 Height Gages 18 Dial Indicators/Dial Test Indicators 20 Gauge Blocks 24 Laser Scan Micrometers and Laser Indicators 26 Linear Gages 28 Linear Scales 30 Profile Projectors 32 Microscopes 34 Vision Measuring Machines 36 Surftest (Surface Roughness Testers) 38 Contracer (Contour Measuring Instruments) 40 Roundtest (Roundness Measuring Instruments) 42 Hardness Testing Machines 44 Vibration Measuring Instruments 46 Seismic Observation Equipment 48 Coordinate Measuring Machines 50 3 Quick Guide to Precision Measuring Instruments Quick Guide to Precision Measuring Instruments Meaning of Symbols ABSOLUTE Linear Encoder Mitutoyo's technology has realized the absolute position method (absolute method). With this method, you do not have to reset the system to zero after turning it off and then turning it on. The position information recorded on the scale is read every time. The following three types of absolute encoders are available: electrostatic capacitance model, electromagnetic induction model and model combining the electrostatic capacitance and optical methods. These encoders are widely used in a variety of measuring instruments as the length measuring system that can generate highly reliable measurement data. Advantages: 1. No count error occurs even if you move the slider or spindle extremely rapidly. 2. You do not have to reset the system to zero when turning on the system after turning it off*1.