Performance Evaluation of DELTA PT 40 in the FCA DS 20 Wheel

Transcription

1 A p p l i c a t i o n s L a b o r a t o r y T e s t i n g R e p o r t Performance Evaluation of DELTA PT 40 in the FCA DS 20 Wheel Project Number: Submitted To: [Company] Test Engineer: Carson McVay Date: 1/28/2015 A T F, I n c o r p o r a t e d W e s t P r a t t A v e n u e L i n c o l n w o o d, I l l i n o i s P h o n e ( )

2 Table of Contents Introduction... 3 Testing Summary... 4 Screws... 4 Application... 4 Tests Conducted (see Procedures on page 5 for test details)... 4 Procedure... 5 Test Preparation... 5 Drive & Strip... 5 Tightening... 5 Repeat Assembly... 5 Drive and Strip Explanation... 6 Test Results... 7 Dimensional Analysis... 7 Drive & Strip... 9 Tightening Repeat Assembly Pull Out Testing Pull Out Fixture Set Up Fastener Dimensions Pull Out Forces Example Force Result Conclusions

3 I n t r oductio n The ATF, Inc. Applications Lab, on behalf of, initiated project number 005 to evaluate the performance of a DELTA PT 40 in FCA DS 20 wheel. Drive and Strip Tests were conducted to determine margin of safety for installation and to calculate the optimal tightening torque. Repeat Assembly Tests were performed to evaluate the long term performance of the joint after several installations 3

4 T e s t i ng Summa r y Screws DELTA PT 40 x 1.46 x 17 TORX Round Washer Head ATF Part Number: P Size: 4.0 mm diameter; 17 mm length Head Style: Round Washer Head Drive Style: TORX Plating: GMW 3200 Material: 1022 Steel, Neutral hardened to RC Application FCA DS 20 Wheel Applique Boss Material: PC ABS Average Hole Diameter: 3.50 mm Tests Conducted (see Procedures on page 5 for test details) Drive and Strip Test Tightening Determination Repeat Assembly Pull Out Testing 4

5 P r o c e d u re Test Preparation To ensure accuracy, a random sample of fasteners were selected for measurement. The pertinent dimensions of the fasteners include the major thread diameter, overall length and head diameter. Likewise, the application piece bosses were measured to ensure stability for testing. The pertinent boss dimensions include hole diameter and hole depth. Drive & Strip Driving torque and stripping torque are important in determining a joint s safety of assembly. Drive and strip torque testing is conducted by driving the fasteners into the pilot holes of each boss with an Atlas Copco electric driver, turning at a free speed of 400 rpm, until the joint fails. The torque is measured continuously throughout the driving process. The measuring apparatus consists of an Atlas Copco Tensor S4/S7 running ToolsTalk PF3000 for data acquisition. The software then collects and translates signals from the transducer into a torque vs. time graph. This graph is interpreted to determine the precise maximum driving and stripping torque. Tightening The tightening torque is the torque at which it is recommended the application be assembled. The tightening torque should be sufficiently high so as to fully drive the screw and generate clamp load, yet low enough to avoid stripping and long term boss damage. An adequate safety factor to compensate for the repeat accuracy of the driver system must also be considered. Repeat Assembly Repeat assembly testing is conducted to evaluate the performace of the fasteners after being serviced multiple times. Each fastener is driven into the test boss using an Atlas Copco electric driver, turning at a free speed of 600 RPM. The fastener is tightened to the tightening torque ten times. The Breakloose torque is measured on the first, fifth and tenth assemblies. On the eleventh assembly the fastener is driven until the joint fails due to stripping. 5

6 D r i v e a n d S trip E xplanatio n 6

7 T e s t R esults Dimensional Analysis Application: FCA DS 20" Wheel Boss Material: PC ABS Applique 1 Hole Ø - Bottom- [mm] 2 Hole Ø - Bottom- [mm] 3 Hole Ø - Bottom- [mm] A B C D E F G H I J K L Average σ Maximum σ Minimum Std. Deviation

8 Fastener: DELTA PT 40 x 1.46 x 17 TORX Round Washer Head Specimen No. Major Ø [mm] Shank Length [mm] Average σ Maximum σ Minimum Std. Dev

9 Drive & Strip Application: Fastener: ATF Part #: 20" Dodge Ram Wheel DELTA PT 40 x 1.46 x 17 TORX Round Washer Head P Applique No. Boss 1 Driving Boss 1 Stripping Boss 2 Driving Boss 2 Stripping Boss 3 Driving Boss 3 Stripping A B C D E F G H I J Average σ Maximum σ Minimum Std. Deviation σ minimum strip-to-drive ratio:

10 Combined Driving Combined Stripping Average σ Maximum σ Minimum Std. Deviation σ minimum strip-to-drive ratio: 10

11 Tightening Recommended Driver Settings: 2-stage Tightening 1st stage target torque: 0.90±0.10 Nm (speed = 400 rpm) 2nd stage target torque: 1.14±0.25 Nm (speed = 100 rpm) Repeat Assembly Application: Fastener: ATF Part #: 20" Dodge Ram Wheel DELTA PT 40 x 1.46 x 17 TORX Round Washer Head P st Assembly 5th Assembly 10th Assembly Specimen No. lnstallation Breakloose lnstallation Breakloose lnstallation Breakloose Average σ Maximum σ Minimum Std. Deviation

12 Pull Out Testing The purpose of this testing was to evaluate the pull-out force of the DELTA PT 40 in the PC ABS boss material. Testing was conducted using the previously calculated tightening torque strategy. Each of the fasteners tested were successfully installed into each of the bosses tested with the recommended strategy. After the fasteners were installed into the boss, the boss was cut away from the material as to fit in to the testing fixture. The fastener for the application tested is 17mm in length and the thickness of the capture material is estimated to be 5mm, yielding a result of 12 mm of thread engagement into the boss material. For the test set up, the thickness of the capture material was increased to 9.50mm. A very similar DELTA PT 40 was used for the pull out testing as was used for Drive and Strip testing. The ATF part chosen for the testing was part P This is a DELTA PT 40 x 23mm. This part has the same hardness and finish as the part tested on the application. With the increased length of this part and the different capture material (test rig) the engagement was able to remain at approximately 12mm. The figure shown below depicts the testing that was performed. Each fastener was measured and documented prior to testing to ensure accuracy for testing. The pertinent measurements for each of these fasteners are also detailed in the table on the next page. Pull Out Fixture Set Up 12

13 Fastener Dimensions ATF Part# P Description Delta 40 x 23 Sample # Head (mm) Thread (mm) Shaft (mm) Pull Out Forces Test # Pull Out Force (N)

14 Example Force Result Trial 5 Pull Out Force Graph 14

15 C o n c l usio n s The objective for this series of testing was to evaluate the performance of a DELTA PT 40 in the FCA DS 20 wheel Applique. The results of the Drive and Strip Tests show that there is an adequate margin of safety available for installation of the DELTA PT 40 into the PC ABS inserts (3σ min. strip to drive ratio > 2). The recommended driver settings are detailed below. Moreover, the fasteners can be reinstalled at least 10 times with the same driver settings without damage/failure of the joint components. Therefore, use of the DELTA PT 40 in this insert design is highly recommended; no issues with assembly are foreseen at this time. Recommended Driver Settings Fastener: DELTA PT 40 x 1.46 x 17 TORX Round Washer Head ATF Part #: P Application: FCA DS 20 Wheel Driver Settings: 2-stage Tightening 1 st Target : 0.90±0.10 Nm (speed = 400 rpm) 2 nd Target : 1.14±0.25 Nm (speed = 100 rpm) Liability Statement The information and technical advice contained herein is given to the best of our knowledge according to the state of technology at the time of this test. It is presented to our customers with the intention of aiding them in improving their product. Please understand that since differences exist between the laboratory and mass production, we cannot guarantee a specific performance or accept any liability. 15